Glad to see another person making the switch(partial that is). As far as which to play 6Max or FR, it's really your choice. Since you are trying to get the feel of cash games as a whole, I would probably recommend FR just because you won't be playing as many hands and therefore aren't as aggressive. with 6Max, we are eliminating the first 3 positions, so your range is going to widen quite and bit and you're going to want to be playing more hands overall and be more aggressive, and that is hard for some players to do.
As far as strategy, there are two ebooks that I would recommend to you.
The ferst one is by Verneer and is mainly a FR guide: Moving Up Through uNL
This one is by Ryan Fees and is a 6Max guide: Ryan Fee's Guide to 6Max (http://www.gamblingsystem.biz/books/2p2NL6max.pdf)
Hope that helps get your feet wet.