couple basic questions
 

I'm working on building up a bike but I'm stuck on a couple of pieces and the search on this site is awful. I picked up a wheelset on clist and it came with a 14t cog. It also turned out that there's no lockring, the kid did something to it and the cog is not coming off. What size crankset should I be looking for and should I be scrapping that wheel and starting over? I'll be riding mostly flat roads and just looking for something to cruise around with.

Unless you can find a 42t or under chainring you might wanna scrap the wheel.
Anything more than that will put you over 80 gear inches which is a bit hefty for flats.

If you want legs of steel though go for it.

80 for flats isnt bad. 85+ is pushing it though.

be a man. get a 50t chainring and stick with 96 gi. >:O

Firs off, what the hell has been done to it and why is there no lockring? Is it a track hub and just missing the lockring? Is it a suicide hub? I actually am running a suicide with a bb lockring on it, but I wouldn't recomend buying one second hand. Try giving it an "anti-rotofix" and get a new cog and lockring (unless you can make the 14 work!).

Just get a little chainring(36t?), and put a lockring on it anyway.

personally run a 46/17 = 2.7 ish ratio....works great overall (some up and downhills, mostly ride flat)

so yea a 42t might be a good starting point at a 3:1 ratio :) for mostly flats

Hopefully the "kid" did not strip the lockring threads and proceed to just rotafix the cog on. If so, you got scammed OP.