If I went with the SQS1072R, would I need a new impeller and/or diffuser? What about with the UQS1102R or HSQ125?
HSQ125 may be an issue because of the back end. I can't guarantee that would fit on the motor support.

As for the impeller, it depends on the service factor of your current pump motor. If the current service factor is 1.25 or lower, then the impeller is fine. Diffuser would not change either way.

Timer:

http://www.amazon.com/Intermatic-T10...W61QF3SM3H6H1T

http://www.amazon.com/Intermatic-PE1...BXFB6W5PGHAXZ5