Splashdown was the one I got mine from. They included liners, hose, heat retentive cover and pump.
The retentive cover stopped the temperature dropping too quickly but you can get pools with heaters and filters so you don't have to do any fiddling about with adding hot/cold water, and they can be filled days in advance. (More expensive though).
Some are hard edged and some are inflatable. Mine was inflatable but took all my weight leaning on it, so no probs there. I am afraid I know nothing about hard edged ones, except I remember resting my head down on the sides in exhaustion so I wonder how comfortable that would be. Maybe have some sort of padding for in case you go for those.
You can get regular sized ones and more deluxe ones - I suppose it depends on what positions you want to be in for labour (maybe) but I went for the bog standard oval one and that was fine for my size (5 ft 8). I couldn't have laid out flat in it however - but then I again I never had the inclination. I was squatting or on all fours for the whole time.
Emptying it was really not an issue at all - dp did a suction thing (not with his mouth!!) and left it to all run out on its own into the bath, then used the pump on the last bits in the very bottom.
Next time I will use a heated pool, because dp was fannying around adding pans of hot/cold water and I want him to take responsibility of dd. When I said this to him he was sorry because he said he wanted to be doing something useful because otherwise he would just have been sitting there listening to me breathe for 7 hours. I have heard this from other men - they want something to do, because in the absence of an emergency it can get boring for them.
hope that helps a little bit