Does honor affect matchmaking?

I don't think it does. Its pretty much a "reward for good behavior/gameplay" that they will rip away from you if you slip up.

Honor does not affect matchmaking. However, that being said, if you're harassing your teammates, not only will your own performance suffer, your teammates performance will suffer as well.

Only if you land in LPQ, which means whatever role you get, you get and if you don't like it, you can hope someone trades or dodge and have to wait the entire timer again. Also you have to play with whatever comps you get unless you want to wait again.

Of course, you can cheat LPQ by playing exclusively bot matches.