Ok. I have a rough idea of what's going on, bear with me though. I'm going to be hrsh and blunt but I have good intentions. I've been through this aswell so have seen the fallout when things go wrong so it's easier for you to know this now and use the benefit of my experience
I'd stop the talking to him about things's he'll learn at school and things that you know he shouldn't know but you teach him to try and catch him out. It really isn't the best way to go. You'll find that when he's at school his life's going to be really difficult because he'll already know what the teacher is talking about, the urge to interupt and correct the teacher is there for a bright child and one with aspergers won't know not to correct them, which will go down like a lead balloon.
You appear to be pandering to his academic needs more then you need to. I know how easy it is, sleep is lovely and my own child doesn't sleep well when he's bored so I really can see why you are doing this but it's really not going to help him, when he's at school there's going to be countless other children all asking questions so he really does need to learn 'not now'. There are also ways of answering a question in a way he'll understand and won't drive you up the wall in the process. I think this is individual to each child so you have to sit and find the key with him. Ds's is to relate things to something he knows, the heart/arteries/vessels for example are like the bus network in the city where we live, the buses leave the depot/station (blood leaves the heart), it has passengers that it drops off along the way (blood delivers oxygen around the body) then it returns to the depot/station when it's empty to collect more passengers.
I also (so sorry) think that this is part of where his umm..superiority complex, where he thinks that he knows more then everyone else..has come from. He's going to run into so many battles with the teachers and other children if you don't help him to change this (again, so sorry).I do suggest instead that he joins a team sports team if you can find one, it's really important that he learns to value other people, that he works in a team and has something to wear him out. He needs to learn that everyone is good at different things so he can appreciate people for who they are. A team sport will help with this.
Academically wise I really would stear clear of anything that's in the national curriculum. Reading's good. I also used to do topics with ds, things like dinosaurs as this is not taught in school and there's a very large scope to it (latin, model making, research etc). There's a term called stretching sideways, this is what this is.
You do also need to teach him that sometimes you just don't know things. This is normal and you need to emphasise that not even he knows everything. I would try and say that you don't know rather then say 'no, I'm not answering that'.
To be honest with you, the social side of life is just as important as the academic, he really does need to wrok in a team and be respectful to others if he's to get along in life so you need to start this now. You need to work with the school in this, you are all in the team that's trying to make your child the best person he can possibly be so you do have to work together. A nintendo Ds was a life saver for me, limited to an hour every couple of days gave me my sanity back.