Speaking of painting... light coats, or heavy?

[Carm]

Depends on the paint. Most good quality paint will work with a single coat. Unless there are major color differences in what was there and what color is currently being applied. In that case, I would suggest a similar colored primer, then paint.

I would only do multiple coats on just finished drywall/texture wall job, after a primer of course.

Edit: It also depends on how it is being applied. Spray vs roll/brush on.
For spray I would do two light coats. For roll on/brush on, I would only use one coat.