I have an M and recently got an M2 and was comparing focus speeds & other things this morning.
Focus is faster than M, using both the native EF-M lenses (I have all four) as well as EF lenses using the Canon adapter. The focus speed of the M & M2 is fast enough for my uses of the M series ... landscape, light travel kit, family photos, etc. It is NOT fast enough for fast sports, wildlife, birding and such. It might be possible (with careful planning/preparation) to get some decent action photos but I suspect the keeper rate will be much lower than the results from a DSLR like the 7D.
I have no experience with teleconverters but you can get the Canon lens adapter (as well as third party adapters) and mount most, if not all, Canon EF and EF-S lenses to the M2. If you get all 4 native EF-M lenses you will have the 22mm f/2 prime plus 3 zooms that include everything from 11mm to 200mm in a small, travel-friendly kit. And the EF-M lenses are quite good.