Even if it is an upgrade version, you can still do a clean install with it. There is a thread around here somewhere that describes the procedure...I think it is as simple as supplying the 98SE/Me CD when asked for it to verify that you own it...after that it will do a clean install.
As far as Home and Pro, the only difference between the 2 is some networking and admin issues, but I recall seeing a thread discussing that in detail, also.
For business, you would probably want Pro.