To answer your first question, yes, Seven Feathers at exit 99 has both a full hook up RV park (very nice from what I've been told) and also has a free dry lot on the North side of the Casino. We stayed in the dry lot just last May. Free shuttle will pick you up if you call the shuttle phone number.
They also usually have good gas prices and also have a pretty nice restaurant next to the gas station.
Full hook up RV park/gas station/restaurant are on the West side of the freeway. Casino and dry lot are on the East side of the freeway.
The CasinoCamper link that several people have already posted can be quite helpful to find free places to spend the night and wager a couple of bucks.
Seven Feathers