May I ask a question? Can I assume no penis (but a vagina) and no procreation possibilities? I assume the answers are 'no' and 'no' but I just want confirmation being a little ignorant on the subject. Is XX the normal female condition?
(I am a straight male so the question itself doesn't apply to me but my curiosity exists anyway)
A female to male transsexual is a person who was born with female sex characteristics but perceives themselves as male and so transitions to live as male and to have many male sex characteristics as is possible.
So a transsexual man would be born with female genitalia. However, there are genitals surgeries to create a penis. But those surgical options currently are not very advanced and don't tend to produce realistic results. They're also very expensive, drawn-out and involve a lot of pain and scarring (especially the phalloplasty). So most of us don't get genital surgery. However, there are very realistic prosthetics that exist that are pretty much indistinguishable from natural male anatomy. (I'm not talking about dildos, either.) You can pee like a male and have sex like a male using those. You can also ejaculate with them, using synthetic fluid that imitates real semen.
Most of us are effectively sterile. We wouldn't want to be pregnant and birth and we also can't impregnate a woman. (Testosterone therapy sterilizes you, plus many of us have hysterectomies and such.)
What determines that there was a transition to male?
Medical transition involving testosterone therapy and surgery. There's also legal transition, which includes changing your legal name and sex marker on your documents and such.
Dunno. I've met some transsexuals. Always found the male-to-females prettier. But as I also find muscular female bodybuilders attractive. Maybe I could have sex with a female-to-male transsexual if he was very muscular.
Testosterone therapy causes the trans man to develop a male musculature.
Can female-to-male transsexuals actually have erections?
Yes. The clitoris is basically the same as a penis and gets its own erections. Testosterone therapy causes the clitoris to grow a bit, but not enough for penetrative sex. However, we can use prosthetics for that.