Replacing pumps/filter

All of my pool/spa pumps have died. I'd really like to DIY replacement and use it as a chance to replace/change the flow of things. Currently, I have 2 skimmers and one drain (spa) all 1.5" intakes. The main drain on the pool is leaking so it's shut off. That goes into a 1HP pump and a sand filter and then that goes back via 2 1.5" returns to the spa and pool. There is a seperate 2" intake & return line for the remainder of the spa jets (4 more) and another 1HP pump.

Am I crazy to think I go to a 1.5 or 2HP pump, a new DE filter and just nix the extra spa pump with some plumbing and valves?

Another question - Sizing a pump seems to be based on the intake sizes, 1.5" = 42GPM etc..., but what about the return? Does everyone just assume they are all the same size and number or does it not matter as much on return since one 1.5" return may go to 2 or 3 jets?

You can increase the size of your return pipe to 2", and then downsize to the returns--they are usually a standard size.

But...how big is your pool, and what kind of pump and filter did you have, and how long did they last? Do you REALLY need to replace both or just one? If either is OK you can replace the other.