Well, all this talk about draining & filling the fishy pool made me think I should try a dry run (more like a "wet" run, as it were - haha) since I am getting down to the wire on this baby coming. So, here's what I learned...
I attached the T-shaped adapter to my kitchen faucet and then attached a garden hose. I put the pool in the living room, which is just off the kitchen so it's very close distance-wise. Filled it up - no problem, took about a half hour to 45 minutes. I took someone's advice on this thread and used cool water first for the majority of the fill before switching to hot. The hot warms the whole thing up pretty quickly. Then I jumped in! My dog was looking at me like I was crazy! The fishy pool is really comfortable due to the inflatable bottom, and it's wide sides are cool because you can lean on/over them with no worries of spilling water.
Then it was time to drain. I turned the water back on at the faucet and reversed the flow. It worked just fine, but it is much slower than filling. Draining takes 2-3 times as long as filling, but it does work. However, I have two things that worked to make it faster. The first thing was a different hose (clear plastic) that I bought at Petsmart that is intended for emptying large aquariums. It works in the exact same way as a garden hose with the waterbed drain/fill attachment on your faucet. I think it was faster because that hose comes in a shorter length, ( I got 25 ft.) so it was laying straight with no coiled sections like the garden hose had. The other thing that made it drain even faster was to lay the aquarium hose along the floor and run it right out the back door to drain outside - I just sucked on the end to get it flowing. It must run faster that way because the water never has to be pulled uphill by the vacuum pressure from the faucet.
Anyway, the two pieces that you would use in a waterbed kit (the T-shaped one, and the little white one) are also sold individually at Petsmart. The "T" was 7.99, and the white piece was 4.79, which might be a little cheaper than waterbed kits which seem to run 16.95-19.95. The aquarium hose was 19.99, and they had longer lengths also. They are all made by Python Products, Inc.
Hope my experiment helps somebody!