Theres a slight difference between what is called a 'paint' sig and a pixel sig, I believe. Pixel is obvious, as in pixel by pixel. I think 'paint' sig refers more to what y0ur_mother does by sort of brushing it in paint.
Go to Window > Optimize. This opens the optimization window. Turn down the number of colors. It reduces quality, but makes the file size smaller. But if you have alot of frames, it may still be too big.
There are already a number of threads on the same topic. Use the Search function to find them. As for pixel fonts, go to a site like dafont.com and search for one.