There is no upgrade path from XP to Win7, it's a clean install, so yes, all your programs will need to be reinstalled.

As for the printer, if you can tell us which HP printer you have, we can tell you if HP says it will be compatible with Windows 7 but since you do not tell us, and HP make hundreds of different printers, it's impossible to know.  We're not psychic and cannot see your current setup!