The 6-2 is identical to a 5-1 where your setter is coming from the back row, with 3 front row hitters. In the 6-2, the 2 setters alternate, so that the primary setter is always coming from the back row.
You might find some good material with a google search on 6-2 offense. Here's one of the links returned that is a brief write up:
Austin Volleyball - ARTICLES
The libero is a defensive specialist and an entirely separate discussion. If you have a libero who is also a great hitter, they can be very effective as an alternate, hitting from the back row behind the middle. My personal favorite is the BIC--back row hit behind a middle quick; I spent 3 months trying to get a libero setup to do this.
The caveat is that the libero cannot attack the ball when it is entirely above the net's height. This can make it difficult, as jumping may put a player's contact above the plane of the net, as seen by the official. I've seen some great attacking liberos shutdown by illegal attack calls in matches (some very legitimately).
As for a substitution wheel, search for "Rotation Locator". (
Amazon Link)