K, welcome. You should find Jean-Claude's suggestions helpful, but in the meantime, I'll suggest that you give more consideration to the Grand Master. This is primarily because it includes the superb M22s, which I've used with great satisfaction for over eight years(and the new v3s are said to be even better!).
Don't worry about power ratings; the 1610 or similar should be more than sufficient. The difference between 75 watts and 90 watts is only about 0.79dB in maximum sound level(e.g., if 75 watts would allow playing a very brief peak at 103dB, 90 watts would do 103.79dB, a trivial difference).
Yes, the surrounds in a 5.1 setup should be a bit(maybe 2')farther back than directly to the side so as to provide a little "phantom" back surround effect in the absence of actual back speakers.
