Reef Plumbing Experts?

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I have a couple of questions for the experts in here:
1) can a Bean animal work correctly with 2x1.5" & 1z3/4" holes, or do they all have to be the same size?
2) with 3/4" bulkheads (returns), would it be fine to run 1" from the pump then reduce to 3/4" at the bulkheads & run a 3/4" pipe into the tank? or can I go 1"--> 3/4" at the bulkhead-->1" into the tank?