I'll answer your questions
The savegames are the ones with .b format. They're tiny because they only store status data, weapons, etc, only tiny pieces of codificated code. You can put it on an usb, install SA in another computer (then start it for the first time, exit) and put the .b file on the Documents > GTA San Andreas User Files. There you go. If you want to copy your graphics settings you can also save the .set file in an USB and then replace the existing one in another computer when you do what I said above.
Hope I helped, any more questions, ask here.