I have a keggle and the Bayou Classic Outdoor Propane Burner. I took about 30min to get my water from room temp to sparge temps and about 45 minutes to boil. It's a great burner. The only disadvantage is the lack of a wind screen. I made some aluminum sides and bolted them to the burner so wind won't blow the thing out. Works great.
The size of the Bayou Classic Outdoor Propane Burner is PERFECT for a keggle. It centers right on there. And it is SUPER STABLE. If I could get the high output burner from the Banjo Cooker on the Classic Outdoor Propane Burner, I'd be in hog heaven. But I don't regret my decision.
In my opinion, I'd just get an immersion chiller. Here's the one I have:
http://www.midwestsupplies.com/stainless-steel-immersion-wort-chiller-w-garden-hose-fittings-50-ft.html
Super simple cleanup w/ a spray off and a plastic dish scrubber. There aren't any hoses that need cleaning, you don't need a pump, and sanitation is super simple. Just put it in the boil for the last 15min. A counterflow chiller has surfaces that are internal meaning you can't SEE them and so don't know if they're clean and/or sanitized. It's an unknown that I don't want to mess with. Plus you really have to worry about sediment going through there and clogging it up. They aren't worth it to me. Plus, if you get some of these hooking your hose up to this baby is SUPER EASY:
http://morebeer.com/view_product/17373//Brass_Quick_Disconnect_Set
About your Oxygenator, I have the Oxygenator and I have yet to use it. I brewed 10gal and drained it into a 14gal Demijohn. I'm with COLObrewer. I had SERIOUS amounts of foam in that baby because of the drop it had from the funnel to the bottom of the bottle. It's getting plenty of air.
I watched a video or read somewhere that oxygenating wort after 12 hours is a good idea. This is where have the Oxygenator kit would help. But otherwise, the drop through the funnel and a minute of good shaking will save you the hassle and the money. Plus, don't know if you know this or not, but the oxygen stone has to be boiled for 10min before you use it. That's one more thing to have to take care of on Brew Day.
I have one and have the peace of mind of knowing it's there just in case, but you don't really NEED it.
Just something else to think about. I checked prices on Midwest Supplies, MoreBeer, Austin Homebrew, and Northern Brewer and far and away, Midwest Supplies prices are cheaper even including S&H. I bought 95% of my setup from Midwest and 5% from MoreBeer with the free shipping. Check it out and see. Just a thought for what it's worth. Good luck!