You PC guy is wrong. Mostly. People upgrade from hard drive to SSD without reinstalling Windows all the time. See
here.
However, it is not uncommon for problems to develop or to follow the transfer to the SSD. So for that reason, many simply prefer to do a fresh reinstall whenever they replace the boot drive.
As far as upgrading the RAM, the best way is to know the make and model of the motherboard. Then look up the specs.