Everybody has a favorite rifle and caliber - usually its the one they happen to own, so you'll get a lot of opinons on your questions about those two items. What you are thinking of getting will work just fine. As others have suggested, stick with the 150 grainer for deer, one that expands rapidly.
I would suggest that you study deer anatomy and shot placement
Whitetail Deer Arrow Placement and Anatomy and practice shooting at different ranges until you feel confident at those distances.
As for mounting the scope, that's a tricky question. I have seen some TERRIBLE mounting jobs done by guys who work at local gun stores. The latest was a scope that was not only mounted crooked, but the tube of which was actually crushed by a guy who over-tightened it. Mounting a scope is not rocket science, and anyone can do a fairly decent job with basic hand tools. There are lots of articles available on how to do it, but if you go to a "professional", make sure he knows what he is doing.
Good luck.