5) Yes that's enough. SH3 is RAM & GFX intensive, your card is the same as mine & I can play with full AA/AF. get 25-30 FPS in port & 80-100 at sea.
If you can, at some point, get another 1GB RAM, it makes ALOT of difference.
As already mentioned, when you first install SH3 1.4b, copy the program folder to a safe location on your hard drive, that way you have a 'clean' copy when needed. All you have to do is copy & paste it over the one you're using and you are ready to go.
