Moosehead is a dangerous lake because it is so big there can be pressure ridges that form over night, so you have to be very careful anywhere on the lake all the time. But Beaver Cove isn't anymore dangerous than any other place on the lake, and there should be plenty of ice, but double check.
I would be very surprised if you can use anything on the lake in mid February other than snowmobiles, or tracked atv's.
I would fish around the islands and shore for brookies, in deep water for togue, and under the ice for salmon.
Beaver Cove is quite easy to get to, right off the main road, and not to far back to Greenville, probably take you 30 minutes or so, but if it took you an hour and a half to get from Greenville to Rockwood you might want to add a little on to that time. $1500 seems on the steep side, but I have no idea.