I'll start of by saying that I have not yet fired the new 7615. However in my vast experience with "big green's" pump rifles, I believe I can answer some of your questions.
Being that this model has a fully free-floating barrel, as do all 760/7600s, it should be plenty accurate for the type of work you describe. I have a 7600 carbine in .35 Rem & it is one of the most accurate big game rifles I own...PERIOD. The carbines that I have seen use a heavier profile barrel than the 22" rifle versions, which adds stiffness and therefor increases accuracy. The barrel on the 7615 carbine (16") is even shorter than that on the sporting carbines (18 1/2"), which should further enhance stiffness & accuracy.
Hope this helps.