newbie here w/ questions

This might sound retarded but I am new to this scuba/snorkel world and I just
purchased a wet suit and was wondering is it best to wear regular underwear
or go naked under that thing or do they sell special under wear for this.
Mind you that I live in San Diego California. I never scuba or snorkeld
before so I want to make sure I am going to be warm enough. Also how much
should I spend on equipment? I already have the snorkel and mask. Thanks