A:
ABSOLUTELY! I was in the same boat- I just upgraded from an OLDER Rebel- The Rebel XT.
NO issues.
The 70D can use any EOS system lens, be it EF or EF-S. In fact the 'kit' lens on the 70D is still going to be of the EF-S line.
I personally already had the following lens from my Rebel as I added them over the years:
EFS 55-250
EF 50 F1.4 prime
They work just fine with no worries. Just line up an EF-S to the 'white box' and the EF lesn to the 'red dot' when attaching to the camera.