Glad to see you made your way here, you'll find lots of good folks who love their REO's and are more than willing to help.
I started out on KR8 equipment, too, and used that for much of my first year. Like you, I got tired of constantly refilling and topping off cartos, and running out of battery.
Firstly, you'll want to know that most of the REO models are threaded for a 510, so your KR8 cartomizers won't work without an adapter. Personally, I prefer the 510 cartomizer offerings that are available now to what I used to use. I think you would be amazed at the performance of a low-resistance cartomizer (1.5-2.0 ohms) compared to what you are currently using. You can use either atomizers or cartomizers on the REO - I have found cartomizers to be more consistent and less fussy, but that's just my opinion. You'll find lots of good discussions on various atomizers and cartomizers here that people have used.
The REO's don't come with batteries or a charger, so you'll have to purchase those separately. Rob also sells extra parts such as battery springs (which are designed to collapse in the event of a short), fill tubes, bottles, caps and o-rings. There is a good thread in the stickies that discusses batteries, chargers and so forth:
http://www.e-cigarette-forum.com/fo...if-reo-your-first-mod-what-you-will-need.html
I generally get about a week's worth of daily use from a new carto on my REO Grand (4-5ml per day). I usually fill a new carto before using it, but some folks just put a new carto on the REO and squeeze to fill the carto - my wife does this and it works fine for her. Here's my routine with my Grand - I start out the week with a new carto, and every night I top off my bottle and put my battery on the charger. Vaping doesn't get much easier than that.
The REO may look expensive, but it is built to last. I've used and abused my first 2 REO's every day for over a year, and am convinced that they will outlive me. They are also a low-risk proposition - if for some reason you don't like your REO, they sell quickly in the classifieds and hold their value. I know I'd be money ahead if the REO's had been available when I first started.
Best of luck, and happy reading! ;-)