Mozilla help

I want to use Mozilla more (no popups, mainly), but I have some problems with it:

A. how the hell do you navigate between windows from the keyboard? MSIE has the Opt-Tab to flip between windows. How can you do that in Mozilla? I can’t find it to save my life.

2. It’s SLOW under Mac OS X 10.1.5 on my G3/400 iMac DV. I know, I know, I should upgrade my computer. Nevertheless, MSIE is fast if unstable and annoying.

Any ideas?