Can I use profoto B10 with canon 5d Eos mark3? Also which umbrella deep size to buy?

Answer 1

Strobes like the B10 are designed for any DSLR. 

The umbrella that you use will be dictated by your technical and artistic needs.

Answer 2

Looks like you can, but you'll need their Air Remote which is another $440. Unless you need certain features this light offers, you're better off getting a regular monobloc with a good quality wireless remote. Also beware of the power (250 W/s). You need to suss out if this is enough power for your situation. You also need to ascertain how many lights you need. Quite often you need more than one light.