Thank you guys so much for the replies!
Re: rotors. I'll have the rotors looked at asap, but I wanted to mention that the folks who sold the car to me had taken it to a mechanic shortly before putting it up for sale, and he'd told them it was likely the tie rod. Should I have that checked, too?
Re: Clicking - I got the oil changed the day before yesterday, actually. I figured that's what was causing the clicking, but it's still doing it. Lifters, maybe? That's what my dad suggested.
Now I have a metallic rattling sound at low speed - like when I start out from a stop. It goes away once I hit about 30mph. I noticed it after I filled the tank, but I'm pretty sure it was doing it - faintly - before that. But not before today.
I'm pretty broke, and not car-savvy (obviously), so I appreciate the help.