HT and outdoor system
CTB,
I think you are on the right track with your system. First, for the main HT, you have a pretty large room. You should consider the Axiom floorstanders, VP150 center, and maybe the QS8's for the surround channels. Definetly go with a 12" sub like the SVS you listed. Since you are using an outboard amp for zone 2, wire for 7.1 in the main HT for a future upgrade.
For the outdoor speakers, your plan will work assuming that you want to play the same source at all 3 pairs of outdoor speakers. After the Amp, I would recommend an impedance matching VC at each speaker location, so you wont have to run inside to adjust the volume. In this case, the speaker selector would not be necessary.
If you want to get a little more elaborate, you could use 2 outboard behringer or audio source amps (or the receiver's powered zone 2 feature) and put the gazibo on zone 2 and the other speakers on zone 3. In this case, your receiver could be playing a different source on the main HT, zone 2, and zone 3.
I would run 3 coax RG6 cables to provide component video to the LCD. You can use the HDMI connection for your main HT.