when you go to dvdfab.com and purchase you are redirected to dvdfab.net
as explained in your other thread both sites are legit and ran by fengtao.
download from dvdfab.com purchases are made from dvdfab.net
you do not have to reinstall once you get your key. just double click the attachment.
you asked which is better full disc or clone. depends on what you want to do as full disc has many more options. but clone will make a better 1:1 copy.