1. Stick with the version you're happy with. But a new update is apparently coming out tomorrow which has a security update which is well worth thinking about.
2. Pro gives you consistent turbo b/c it connects to 5 Ultrapeers where as LW Basic only connects to 3.
3. Average 56 kbps dial up = 7 KB/s - overhead (about 2 KB/s) = 5 KB/s
4. No. Only if you get super-dial up which some isp providers offer or you use broadband or cable.
5. 256 MB RAM is a little small nowadays, you should be looking at 512 MB at least. A faster cpu won't hurt you.