IMHO, you should buy a name brand spacer, like MM,
Eibach or other. But if you must go with the cheap stuff, at least make sure you are getting hub centric spacers. There are endless numbers of posts here on the importance of using hub centric spacers.
As far as how wide to go, you should measure. Take a straight edge, put it up against your tire, then measure the distance between your tire and the inner most edge (that is, the closest point to the tire face). That distance will be your maximum spacer. Some people push it even further for the completely flush look. But IMHO that is too far out, plus you risk cutting your tires on the fender.
As far as different sized lugs, that will depend on the size spacer you get, and the design of your wheels. If your wheels have a space where the lug and nut will go, then you will be fine. Mine have that. If your wheels have a continuous surface that sits up against your stock hub, then you could have a problem (especially with 1" spacers).
Go to Maximum Motorsports' web site for more comments on fitting wheel spacers. And while you are there, pick up a set of quality spacers from them.