I love this Mirror trick: https://www.youtube.com/watch?v=ZD0_5HFMPIg
Any tips on getting it to fit on a DSLR?
"C) No Jump Cuts in General" - I think you mean 'no accidental Jump Cuts'.
You can probably find the 7D for under 1,000 right now. Also this tool is great for comparing cameras in this price range: