Kfishcat,
Mossberg got smart and started making replacement barrels for Remy guns. They fit and work just like the factory barrels made by Remmy, but they are generally less expensive. You are NOT buying a barel made for a mossberg and putting it on a remington, you are buying a mossberg barrel thats made FOR a remmy...so you are safe. They are good quality and I am planning on getting an 18" Mossy barrel to go on my current project 870. Midway sells the 18" mossberg barrel for $99 and thats about $30 cheaper then the same version made by Remington!
"Wingmaster" means that your gun has a shiny blued finish rather than a dull parkerized finish. Any finish will work, its whatever you are happy with. The Mossberg barrel in blue will look great on your gun. The great thing is that it takes about 30 secs to swap barrels so you can use one shotgun for bird hunting and home defense simply by switching barrels.