There usually is a 10 foot rule (most cities) for ANY structure (fence, house) that you should be aware of. This also applies to overhead wires. (I saw the power pole in one of the pics - but could not tell if it goes over your yard.

Talk to your building dept to get a list of rules before buying anything.

After that - I think I would look at an oval vrs a round pool. I think you get more pool with an 18x30 vrs a 27 foot round, and lose less yard.