Seems I'm a bit late to this party. But to answer some questions I saw (that have likely been answered already):
You will need a tiller wide enough to cover your tracks. Preferably one that is slightly offset, so you can turn and still cover your tracks. I have a 6ft woods on my tractor, I always turn to the right.
You will defiantly want a slip clutch. You will hit rocks, tree roots, underground pipes and electrical, the dog's bone, etc. The slip clutch will save you a ton of down time.
Hitting such objects is not typically a problem (unless its one of the pipes or electrical, but that's another issue).
Your tractor can easily run a 6ft tiller that digs down to about 7inches. I know, because that's what I have on my tractor, and my tractor is the same as your tractor (minus the cab).
King Kutter is a great economy brand! I use that brand for implements I know I'm going to beat up, like my rotary mower. I beat the hell outta that thing, and I spend a lot of time repairing it. But a tiller? No, I probably wouldn't skimp on a tiller. They are a bit more complicated than a rotary mower. King Kutter seems to cut corners almost everywhere. Thin metal plates, lack of reinforcement at key locations, and some of the worst welds I have ever seen on a manufactured implement. But, if you only use it for an hour per year, then it's hard to justify the cost of a name brand implement. If it breaks down hard, go buy another one and you will still be spending less than a main name brand.
As for speeding up your time in the field vs plowing and disking. That depends. Tillers are S-L-O-W! When I'm tilling, I'm in Range 1, Gear 1 @ PTO Rpm, and its almost too fast for my soil. I have to take a shallow pass, and then a second deeper pass in my garden. My tractor does not have a creep gear. It gets the job done, but its no speed demon.
For anything over an acre, I'd probably plow and disk. I explored that when I was hired to manage a 10 acre pasture lot for a neighbor. Plow and disk or till with tiller? I opted for the plow, but my neighbor sold the lot before I got to work it. (New neighbor put in a park!)
Hope this helps.