Peter's Yahoo Answer
Q1. Heterosexism: 'Therefore' is the key word here. By assuming that everyone is heterosexual you can't help but marginalise other orientations. (a metaphor: Sexism would be assuming every businessperson is a man. This marginalises, as well as erases and oppresses, women in the business workforce.)
Q2. The Hormone 'T': Quick lesson you should've gotten in high school sex ed. When human's go through puberty they start releasing more of certain hormones that cause their bodies to develope in certain ways. In general, women have a higher level of Estrogen (than Testosterone) and men have a higher level of Testosterone (then Estrogen). If a cis woman (a woman born with female sex organs) goes on estrogen she can overdose and die. Same for a cis man taking testosterone.
Trans people take either testosterone (T) or estrogen (E) to balance out their hormones. T makes bodies more sweaty, more hairy, can make voices drop, etc. Basically all the typical things you see boys go through during puberty. E is similar, but makes a body go through the typical things a girl goes through during puberty.
So after that minilesson - no a MtF would not take T as she could get sick and die from it. A MtF would take E as that is the 'female' hormone.
Q3. Transsexual: this is now more semantics than anything. There are three main words used to describe queer genders (aka. anyone whose gender doesn't match their sex perfectly). Transgender, transsexual and genderqueer. There are strong arguments for all to be the 'top group' (and for the rest to be subgroups). At the moment, popular opinion says that transsexual is 'out dated' and genderqueer isn't a well known term so usually transgender is the word used to describe anyone with a queer gender. Saying 'trans' or 'trans*' are also good options.
Transsexual and transgender are basically interchangable. They refer to the same condition and far merely used based on preference. MtF would be a subcatergory of both transsexual and transgender equally (as well as being a sub catergory of Trans and trans*).
Q4. Queer Terminology: In the end, every term means what it needs to mean. If you read a definition somewhere and someone who identifies as the word doesn't exactly match the definition you read then don't sweat it and just agree with the person.
I'll answer what I can, but most are just colloquial (casual) terms with little set meaning beyond what any queer person wants it to mean at the time.
Gynephilia is an attraction to women (gyne=women/female; -philia=attraction). Similarly there is gynesexual which is either sexual attraction to women or sexual and romantic attraction to women. (As well as gyneromantic which is a romantic attraction to women).
On that note, Androphilia is an attraction to men (andro=men/male; -philia=attraction). Similarly there is androsexual which is either sexual attraction to men or sexual and romantic attraction to men. (As well as androromantic which is a romantic attraction to men).
Gender bender usually refers to a certain subset of crossdresser who can pass for a different gender (Ie. a gender bender girl would be a girl who is crossdressing as a boy and crossdresses so well that most people automatically assume she is a boy). This is a common plot device in manga/anime (like Hana Kimi or Host Club).
Gender diverse is... well you can't really get more obvious than that. If it's in reference to a person then that person has a diverse gender. If it's in reference to an organisation/etc than that means they have many kinds of gender (or are accepting of many kinds of genders).
Epicenty is a genderless or gender neutral term. It doesn't seem to typically refer to people, but more language and art. It usually refers specifically to a loss of masculinity, but is also a loss of gender distinction in general.
Between Genders is usually for monogendered transgender people. That is, for transmen or transwomen who don't personally feel that they are 'real men' or 'real women' yet but have definatly left behind their AAB (assigned at birth) genders. Transgender people who are in the process of transitioning.
Aphroditus is an actual Greek god. Aphroditus (a male form of the name Aphrodite whom you may recognise as the godess of lover and fertility) is depicted with a women's shape (ie. curves, hips and breasts) but also with a beard and penis/testicles. Proving that people where trans* even in Ancient Greece, Aphroditus was celebrated in 'transvestite' rites (though presumably this refers to transsexual and transgender rites, too).
Agender (which is not hyphenated) is lack of gender (a=not; gender=gender identity). This is those who don't identify as any sort of gender at all.
Intergender is the gender equivilant of intersex. They identify somewhere between male gendered and female gendered. (inter=between; gender=gender identity).
Multigender means identifying as more than one gender. This might be identifying as a man and a woman or it might be identifying as three or four (or more) genders. (multi=many; gender=gender identity).
Other gendered is a term that should be used delicately as 'other' is a word that is commonly found offensive to minorities. Now that that little disclaimer is out of the way - other gendered is generally another term for third gender (or sometimes for genderqueer). It is an identity that is not man or woman (including trans man or trans woman, of course).
Queer heterosexuality is basically deviance from typical heterosexual roles. It refers to any heterosexual relations that isn't the strict "feminine woman submits to masculine man". It was a term thought of during the Women's Revolution in the 90's and - since gender roles are minimal these days - isn't much used these days. Queer heterosexuality can also refer to someone who identifies as heterosexual but is very VERY occassionally homosexual or skoliosexual (skoliosexual being an attraction to people who are other gendered or third gendered or genderqueer).
Two-spirit is a term exclusive to certain Native American tribes. It refers to a person from that tribe with both a man's and a woman's spirit within them, making them both a man and a woman. (Using this term if you are not from these certain tribes is appropriating and it is erasing and offensive).
Q5. Transgender and Sexuality: Using your example, if you are a girl who only likes boys then you are heterosexual. If you are a girl who only likes cis boys and trans boys then you are still 100% bonafide heterosexual.
First mistake - do not class 'transgender' as a whole different gender. That's what genderqueer is used for. There are three main classifications of gender: men, women and genderqueer. If you are attracted to men then you are androsexual. If you are attracted to women then you are gynesexual. If you are attracted to genderqueer then you are skoliosexual.
If you are attracted to men and women then you are andro-gynesexual. If you are attracted to men and genderqueer then you are andro-skoliosexual. If you are attracted to women and genderqueer then you are gyne-skoliosexual.
You are androsexual if you are attracted to any kind of man - cis men and trans men. You are gynsexual if you are attracted to any kind of woman - cis women and trans women. If you are attracted to someone who is not a cis man, a trans man, a cis woman or a trans woman then you are skoliosexual.
People who are andro-skoliosexual and gyne-skoliosexual often identify as heterosexual (which is actually pretty erasing and offensive to genderqueers) as it is an 'easy' label to describe. Other than that, andro-skoliosexual and gyne-skoliosexual people identify is a number of different ways. The most common are heterosexual, mutlisexual, polysexual or just queer. Or, sometimes, a label they've made up or found on their own that feels right for them.
For the record, a pansexual is an andro-gyne-skoliosexual. (Ie. Someone attracted to the whole spectrum).
A year+ of extensive research on gender and sexuality (as well as a touch of person experience and second hand experience).
Also, remember that Google is your friend! Often Googling terms leads to quick answers.
I hope this helped :D