B.R.
Mostly for the sake of your daycare provider I would skip pull-ups and go straight to big boy underwear. Ask them because they might not feel the way that I did, but I HATED pull ups in the daycare setting- I would have much rather changed poopy underwear. Also, though, I think that pull ups are still too much like diapers and kids feel more like "big kids" when they get real underwear.
I would also avoid using rewards. If you need rewards to get him to go then he's not ready. And if he is ready, you won't need them. Using rewards teaches children to expect external motivation and underrates internal motivation. Teach him to instead feel pride in his accomplishment by giving him ownership ("you did it!", etc). Also, rewards will be difficult to do in the daycare setting because, depending on what you use, the caregivers may not be able to use them because it would be unfair to the other children. Similarly, you couldn't save them up to give when he gets home because children need immediate feedback- he won't relate the reward with the behavior.
I like my potty, and it turns into a bench like you want. It's by boon (I bought it at mom4life.com, but I've seen it since at babies r us, too) and it's also really cute- just a little more expensive than you want, at $40, though. But really, I don't think that the potty matters. Your sister may have been struggling because her son wasn't ready, not because of the potty she chose. If he's ready it shouldn't matter. Just find one that suits your needs. I don't even think they all three need to be the same because at his age he understands that a potty is a potty, even if one looks different than another. One step ahead has a lot of neat choices, especially if space is an issue at any of the sites or if you want to buy something portable. I just looked at that urinal and was like "seriously, what a waste." You would still have to buy a potty, so why buy both? I mean, is it realistic to teach your son to go in a urinal when he is going to have to go in a toilet more often than not? Plus it's just an unnecessary expense. As far as the big boy underwear, I would talk to your daycare providers and see what they prefer. I think you could be effective either way as long as you are consistant. While I don't think small rewards are effective it could be really exciting for him to help pick out big boy underwear after he has gone two days (or whatever you feel is appropriate) without an accident- again, it's empowering to him because instead of you just giving him something he's helping to pick something that he will actually use and that will make him feel like a "big boy."
Another suggestion- potty books. Anything you could find is probably good.