RE: is the .17 enough gun?
As stated previously, the HMR is fine for everything up to Fox. For yotes you need to focus on placement and try to keep shots under 100yds. As for accuracy, I've found that you have very little drop out to about 150 or so. If you want to stretch out to 200yds, check out the .22Mag with the polymer tips. For more power and range than that, you'll have to go with either a 5mm Remington or one of the smaller centerfires.