There's no way to adjust camber in the rear, and with how the rear (double wishbone) suspension works on these cars, you see more negative camber as the car is lowered. What this means is that if you don't do camber bushings or lower control arms, you're going to see unnecessary negative rear camber after a 2 inch drop.
Camber bolts are for the front, because the front is a MacPherson setup and will not gain really any camber upon lowering. There's also no way to adjust front camber from the factory, and camber bolts or crash bolts let you adjust it a little bit. The factory camber setting is close to 0, which is suboptimal. 0 camber is not good. You want a little bit of negative camber. Cars have to turn, and negative camber is important for grip during cornering.
Generally speaking, around -1 to -2 up front, with around -1 in the rear is about the right place to start when thinking about performance alignments on street cars. More aggressive driving situations will likely require even more negative camber. Anything more than -3 will start to wear tires unevenly. Generally speaking, more negative rear camber than negative front camber will lead to understeer.
You want to also be cognizant of toe changes, and lowering will likely affect toe. You don't really need any toe on these cars. You might need a little rear toe in, if you go forced induction later on just to keep things more stable at speed. Toe's also what wears tires the fastest.
For the drop you're aiming for, you should get rear lower control arms AND camber bolts.
Less than an inch is a mild drop, and will not necessarily require camber adjustment in the rear, unless if you're anal about it. You should still do camber bolts to keep things balanced, regardless. You're changing the suspension geometry when you lower the car, and you're going to have to correct it, unless if you're okay with it being worse or weirder than stock.
I'd get an alignment right away; if not on the same day, within the week. If you don't want to deal with lower control arms, then you might be better served starting at an inch of lowering and see if you like the way it performs at that height, and seeing how much negative camber you have in the rear vs. the front.
Or if you don't care about understeer, oversteer, or geometry; just slam it, zero out the toe as much as you can, and call it a day.
tl;dr version: there's no factory camber adjustment, and lowering will increase negative rear camber. Camber bolts and lower control arms can be used to bring the front and rear camber, respectively, to acceptable/optimal ranges. Get an alignment, ASAP.
Also, good reading:
http://www.ft86club.com/forums/showthread.php?t=67345