Which ADL is it? Maybe Im confusing it with another model, but is it a wood stock, or the black composite ones?
I'm not terribly familiar with the ADL line, I apologize.
As far as accuracy, noone can tell you how it will be. Ive seen 2 exact models of a rifle shoot the same ammo, and while one liked all of it, the other hated most of it. All barrels are different.
But in general, if you do your part as a shooter, and find the load it likes, you should be able to get small groups at 100 yards. As far as size?
I could hit quarters all day at 100 yards with my .30-06 700 Mountain rifle with factory ammo(until a terrible flinch set in). If you dont have a lemon, and you are a decent shot, theres no reason your ADL cant match that. The .270 has some high B.C. ammo available for it, so thats a plus.
The scope you have is fine, no worries there.