I disagree with the poster that said the OKW buses are horrible - they just work differently than at some of the other resorts.
With 3 kids, you will probably want to request a room near the HH - they just added a slide at OKW main pool.
I'm not certain how the busses are working at OKW right now - it used to be they would stop at the HH house both on the way in and the way out of the resort. Don't know if they are still doing that.
But you'll get a LOT of great info if you post your OKW questions on the Disney Vacation Club board. The people there have info on almost anything you can think of about OKW.
OKW is my home resort, and we always stay in a 1 bedroom - it is a small apartment, with a full kitchen, full sized washer and dryer in each unit (for all sized rooms except studios). So you won't have to worry about "finding the couple of places to do laundry" that I read in another post - that person obviously didn't do any research before going. I think it was the same person that complained about the buses at OKW - again, advance research makes for a better trip.
I do see you're bringing 3 kids - that makes 5 people in a 1 bedroom, which is a hot topic on the
DVC boards (not officially allowed, though lots of people do it). Just be aware that OKW will not provide a cot nor extra bedding or towels - you'll get bedding for the king sized bed and the double or queen sized fold out sofabed. And you'll get towels for 4 people.
So you may want to bring extra towels and/or bedding and some poeple do bring a blow up mattress for their 4/5th people, depending on if your kids will sleep together in the sofa bed without any problems.
Again, I think you'll get more info on OKW on the Disney Vacation Club board, so I'd suggest posting your questions there.