2. IMHO no
3. the power consumption, heat, and noise would most likly be lower but not by much.
If you are overclocking(even if you are not an extreme overclocker) then you may want to look at a different brand. EVGA's non classified versions of the 770 use reference VRMS which are fine for stock and small overclocks, but of you want a higher clock than the SC then you may want to go with the classified version(if you want to stick with EVGA) or a Gigabyte, MSI or Asus card as they use better VRMS.