he'll probably ask me where I learned the word hymen

LOL

I just wish I can figure out a way to assure him Im not anxious because he's trans

You kind of are anxious because he is trans. It sounds like you are attracted to the idea of fucking him in the front, but are nervous because you have never done it before and you think you might be bad at it, or that you might not like it. You also sound like you're afraid you will offend your boyfriend if you fuck him there, even though he wants you to do it.

I'll be his first time being penetrated, so I definitely want it to be good for him. It'll be my first time in a vagina, too.

That is a lot of pressure for your first time doing something, not to mention the pressure you're putting on yourself. Are you worried that if you explain you're nervous about having sex with a vagina, he will think you're not attracted to him because he's trans? You said you get hard thinking about fucking him there, but when it comes down to it you can't do it. That sounds like performance anxiety to me.

I've fucked my previous boyfriends before, but I'm told its a very different experience. Back hole from front hole I mean.

I personally have no idea, LOL. I've been told though that it feels really good. Some guys are repulsed by it and can't get it up, and even if they can they don't like it, but the ones who like it say it feels really good. I have heard some guys say it feels different from an ass.

IDK. If its stretched it goes back to its same size and shape afterwards, it doesn't stretch out easily and it is self-lubricating which some men like. You can fuck a vagina a lot harder and rougher than you can fuck an ass, and it will usually grip the cock. There is also a place inside similar to a prostate which will make the vagina-haver cum immediately if you hit it from the right angle, but it is really hard to hit (called the 'g-spot'). I've only ever hit mine on accident. If you fuck him and he cums when you're inside him, his hole will squeeze around your cock, which is normal. He also might lose interest in having something inside him after he's cum, which is also normal.

You don't need to prepare him as much as you would for anal sex but its good to stretch him a little bit before penetration. If he has some of his hymen he might bleed a little bit, but if he's had a lot of action down there he probably doesn't have a hymen.

You can't go ass-to-vag because it can cause some serious infections. Other than that it cleans itself which is weird. Its the cleanest place on the human body if you can believe it. You should use spermicide if you go bareback, because unless he has a hysto, he has a small chance of pregnancy. However, his chances aren't as high as they are for a cis woman. So there's your vagina 101 LOL.

Like I said, some guys just find it to be a turn-off. They just want a guy with a penis, and that's ok, it is actually normal. You can always do other stuff if it makes you too uncomfortable. Also if you're not ready, but you do want to fuck him, you don't have to do it right away. You can explain to him how nervous you are and he should understand.