1) Moving speakers while great in theory is likely going to get boring quick and either a) you'll not bother or b) buy more 
2) Only if your TV supports 5.1 over optical (you'll need to check)
3) To get 5.1 from other sources when their TV doesn't support 5.1 over optical most people buy an optical switch.
2) Only if your TV supports 5.1 over optical (you'll need to check)
3) To get 5.1 from other sources when their TV doesn't support 5.1 over optical most people buy an optical switch.