Yeah, a guy wants someone who's above the age limit...that's TOTALLY pedophilia! Especially if he's looking to do it with someone who's already a fully physically developed male! That's totally a pedophilic desire!
Anyway, peanut gallery aside, some advise on sex:
First of all, cut yourself a break--you're new to this. Don't expect to be able to blow his mind on your first time. If he expects that, then he's probably not a good sexual partner, in all honesty. Especially if he knows you're a virgin
Deep throating is something that takes practice. Generally, it's about opening your throat and convincing your body not to gag from the feeling. Obviously, that's known as "suppressing the gag reflex." I would stick with heavy licking (that's basically more of the blow job than any actual "sucking") and insertion that's comfortable to you. If you wanna be adventurous, try taking it down your throat, but don't force yourself. And if he tries to just shove it down your throat, he's probably going to gag you, choke you, and wind up with stomach acid bath on his dick (just more reason for him to be a slow and understanding partner).
But, I find that length usually isn't as much of an issue as girth is. If he has a medium length disk, but it's wide and girthy, it can be hard to get in. A longer dick that's average in width is much easier to deep throat and blow. If it's just to girthy, don't force it or it'll probably hurt him because of your teeth.
If you end up fucking, use a condom, obviously (which you could also be using for the blow job, btw). Make sure he really gets you ready by slowly fingering you with lots of lube and gradually adding more fingers to get your anus and rectum used to a larger object entering it. Additionally, he should be helping you relax, which will make penetration much easier. Foreplay is a great way to do this, so it's one more reason for him to be a good partner and get you riled up and horny and comfortable. As he lubes you up you can also make it easier for him to finger you by pushing out like you're going to poop. Pushing out causes the sphincter to relax and open. Tensing will obviously cause the sphincter to clench and tighten. While he's fingering you, he can also gently massage your prostate to make you feel good and get your dick hard.
When he starts penetrating you, his condom-covered dick should have a good deal of lube on it. As he starts to press in, push out again (re: like taking a dump) and it should slowly enter. If he's really big and it starts to hurt, he should sense that you need him to wait (and tell him to wait if you feel like it's too big or it's not going in or hurting) and he should stop and let it sit where it is until your anus gets adjusted to the size and feel. When you feel ready, give him the okay and he can try to go a bit further in and repeat until he's able to go in comfortably inside you. You may need to apply more lube during this process and it never hurts to have a good amount.
As he gets deeper in, he can start pumping gently and slowly to get your rectum to open up a bit more and get used to the moving action. If it hurts a great deal, tell him so and he should stop and let you get used to the penetration or pull out and gently continue fingering you to help you relax and open up.
If he's able to enter and fuck you comfortably, then feel free to go faster and harder and wilder.
Try out different positions, too. There a bunch of good positions for prostate stimulation. Generally, if you're both facing each other, then his dick (if it curves up slightly) is in a good position to hit your prostate as he fucks you such as missionary position or sitting on it and facing him (reverse cowboy, my personal favorite). For missionary a good way to get some prostate stimulation is to have something like a pillow under your butt to give your hips more of an upward boost and make his disk pass under your prostate. or, if you've got some good ab strength, you can just pull your legs up like you're doing leg lifts and raise your ass to achieve the same effect. If he does more downward thrusting, being on your stomach, doggy style, or sitting facing his legs (cowboy) are all good positions.
But as you can probably tell from this post, the biggest thing here is observation and communication. You can provide the best pleasure for him by watching him while you blow him or stimulate him and see what really gets a reaction from him. Does he gasp or sigh when you lick his neck or his ear? Does his body tense in a good way when you pinch, lick, or brush his nipples? Does his dick jump when you kiss him? Does he growl when you moan or call his name? What about if you lick around his navel or play with his balls? All of these kinds of things are great indicators to what you're doing that really gets him going or pushes his buttons. Additionally, I generally find that things I like or the places I would want to be touched and the way I'd like them to be stimulated is a great instinct to utilize on your partner. More likely than not, they like it too and if they don't, just move on to the next thing.
And of course, it's not at all up to you to provide the pleasure. It's his job as a good partner in bed to make you feel good. He should also be observant of what turns you on (though sometimes, you just gotta be more obvious or vocal about it). If he's not getting it, try gently guiding his hand to where you want him to touch, or give a bit of a more audible groan when he does something you like. If he's unwilling to do something that is reasonable to help you get going, then maybe he's not the best partner (which you can consider in the future).
And the MOST important thing is that you have safe sex and that you feel comfortable and in control. If something doesn't feel right, or hurts, or you just aren't ready and want to stop, you should always be able to. If you don't feel like he's going to listen to you or if he's pressuring you to take it further than you're ready to, tell him to stop and be assertive. You don't have to do anything you don't want to and he should respect that or you're outta there.
If he shows you a good time, then you're more likely to come back and have some great chemistry and future sessions than if he makes you uncomfortable and hurts/freaks you out and you never come back. You've got the power here. Good luck and have fun!