Getting a new house, and I want to install a pond. Any tips?

This back yard sounds like it already has drainage problems, and it's maybe not even built yet? I'm not sure a pond is going to be the landscaping answer you're looking for here, and I'm not even sure this home sounds like a wise purchase. But, that's not what you asked, either. Use rubber pond liner for your pond, it comes in any size and conforms to any shape. Pick any submersible pump you like (depends on the size pond, how much water you want to pump, and how much electricity bill you want to pay). Little Giant is a good pump brand. You'd want a submersible filter, too, sized to match your pump.