1) Hard wired is always better. Less interference, higher speed. Again, as you've been told before with your many many Xbox issues, check with Xbox support. There hasn't been an update to the T1200 recently so it's likely the Xbox.
2) Microsoft has no relation to Telus or the software running the boxes currently.
Another option I've been exploring is "powerline".
I don't get 500Mbps, but I do get a much more stable 33Mbps for streaming. Individual performance will vary with distance and interference.