RSR is the exception of the busiest attraction at the park, usually 50 minutes or so.. the rest of the attractions usually don't go over 30. On last thursday the lines were SUPER short (Disney standards) so space was about 20, Indiana Jones 25, Matterhorn 10-15, Luigi's Flying tires 10, screamin' 5, etc. So you've picked a great time to visit the parks!
There will always be lines but they usually aren't too bad in the middle of the week. In my experience Tuesday and Wednesday are the best days for lines, but Thursday isn't bad either. You're probably looking at anywhere between 20-30min wait times.
As far as RSR goes just expect a long line. It's a new and very busy attraction. Use the restroom before hopping in line and just go for it.
Please... put Guardians of the Galaxy in Tomorrowland.