Would I have to buy MS office for Mac so I can view all of the word doc's and excel spreadsheets etc, or is there built in software that can read all of that?
Yes, you would need to buy Office for Mac. Or you could get StarOffice (I think it's staroffice... the free open-source version of Office for Mac)
The bonus of Intel-based Macs is that you can install Windows in a dual-boot setup, and have Windows programs in Windows, and Mac programs on the Mac side.