i would say the best place to buy your shotgun would be at your local gun shop...you might pay a little more there, but it is worth it. the guys as dicks/walmart, and i have found here, at gander mountain cant tell the different between the shotgun you want and a hole in the ground. its also good to support the small guys. they will have lots of knowledge and be able to help you in the future as well. its good to sort of establish a home base, a place you can go for all your shooting needs. you get more than a gun, tips on where to hunt, ammo to use....kinda like this board....
...as for the gun the combo would work fine, if you want a higher grade get the wingmaster and buy a rifled barrel later, it is up to you...as everyone said you cant go wrong with the 870.