As far as your scope rail question...I believe the rails are all the same for any NEF/H&R except the Ultras.
What I found with my Sidekick was when I mounted the scope my line of sight was too low on the straight style stock. So I ended up replacing the original wood with monte carlo composite.....made all the difference I needed.
Clean your barrel really good,,,,,,I also used bore polish on mine. My gun likes the PowerBelt 295 hp and two 777 50 grain pellets. But don't be afraid to experiment. Great shooting rifle.