Yes I had done both of those already to my caviar black HDD also moved my iTunes folder to the secondary HDD.
Well I doubt most geek squad places will build you something from scratch if you bring in the parts. They might I'd they are a store like mine. I would do this but I'm sure it would get pricey to be honest with you. Labor for us is very expensive, besides Doing the build yourself is half the fun!! Don't be afraid to do it, research an preparation are key and you will learn a lot about your system.