Great info here, so I cannot add much. I have a 10 gallon kettle with a ball valve and a bazooka screen to catch anything that might get thru the bags. I use a smaller bag for my hops and usually use pellets. My kettle is a GasOne that my wife got me for a present. It is a great kettle and I would recommend it, but it was a bit pricey I think. I have tried full volume and sparge methods and both have worked out. I am going to look for a colander to fit inside the rim of the kettle as my bag will mushroom out and I end up spilling some on the floor and on my burner. But, other than that, I really like the kettle and am getting used to how it holds the heat.
Also, the kettle came with a false bottom, so eventually if I want, I can turn it into my mash tun and get a separate kettle to boil with, but that is down the road, and to be honest, at some point if I can finally get my process figured out, I might look into the Anvil all in one. But I digress. Good luck and Rock On!!!!!!!!