I would go 64 bit regardless. There's no reason not to anymore unless you're in a corporate environment.
There is no full version anymore. Technically the only sku consumers can buy is the OEM version. They changed the licensing terms to merge the transfer rights of the retail license to the OEM sku though, so consumers get a better price, and most (if not all) of the same rights as buying a retail license before under previous versions like Windows 7 and Vista.