When you take a MAS prop out of the package, it has a lot of mold flashing. You want to sand or shave that off. You'll actually pick up RPM by doing that, and the prop is more efficeint, you get more pull, and the prop isn't as sharp. APC props also have flashing, but not as much. And they should have really sharp TE's.

Also, be sure take any price tags or saftey stickers off. And you should balance your prop as well.

Wing dowls, if they are exposed wood, should be fuel proofed, like any exposed wood. I wipe some epoxy over them. Yes, you can modify the plane to take a larger dowel if you want. Just be sure you don't weaken the area that holds the dowl in place. If you want to do a bolt conversion, you can do that too, but I've actually seen more wings come off when a botched bolt conversion let the bolts pull through the wing than I've seen dowel failures. Fwiw, I use hardware store dowels all the time with no problem. Just look for ones with a tight, straight grain.