I’ve been looking at "pendant lamps" for my apartment online, but I bought a pendant lamp at a yard sale and found out that you have to drill it into the ceiling to make it work. I just want to know what to search for to find a light that doesn’t require drilling, one that just plugs in directly to an outlet.

It’s called a swag light. But you can wire a cord to it and plug it into the wall. Just get about 20 feet of lamp cord, replace the wire that’s there now, and put a plug onto the other end of it.
That would be a swag lamp. You only have to screw a hook in the ceiling to hang the chain or lamp.
LED Strip light can adhesive on the wall. good for decoration http://www.eledlightmall.com/led-strips-c-3.html