Quick changes are definitely the way to go to make swapping calibers faster and more convenient. You want to be able to set up your dies once and go, not have to dial them in every time you switch calibers.
If you are going to wet tumble you need stainless pins, not corncob and brass polish. I wet tumble with lemishine and car wash wax. I mostly do this so my rifle primer pockets get clean but to each their own, dry tumbling works fine as well.
I agree with Sarge on the dies, no need to spend twice as much just to have Dillon dies. I've used Hornady, Lee, and RCBS on my 650 without issue.
You can never have enough primer pickup tubes, take the money you're saving on non-Dillon dies and buy more.
I personally don't use the powder check system, and eventually you'll want a Mr. Bullet feeder and will need that station anyway. I say skip it and do a visual check as you go.