Mounting a scope is no problem - the barrel is pre-drilled for scope mounts. I used the Knight See-thrus on mine, but Knight also has a standard set of mounts that can be used as well.

Personally, I think pellets make great rabbit food - but aren't that great for muzzleloading. At best, the pellets only allow you to adjust your powder charge in 10gr increments by alternating between the 30 & 50gr pellets. I prefer moving in 5gr increments as my USAK often prefers it that way. The Pellets will shoot ok out of the USAK, but the odds are you won't find your most accurate loads with them. The only misfire I ever had out of my rifle was when using pellets - so I don't trust them to hunt with, but I do play with them from time to time at the range.

Like I said before, if you stick to bullets 300gr & up you'll be well pleased with your accuracy. Some common bullets to try are the 300gr Hornady XTP Mags and Hornady SST sabots - shoot those over 80gr of Triple Seven powder for excellent accuracy. You can also try the 348gr PowerBelt bullets over 90gr of Triple Seven for a near identical point of impact to the Hornadys.