Pipe size and recommendations- remote manifold w/ recirc-tri level w/stacked baths/laundry

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Tegan Easton

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About to commence installation of a remote manifold in a tri-level home.

pex-a/propex/expansion pipe

The bathrooms and laundry are all stacked at the same location.
Laundry hookups
3 sinks
2 showers (w/ body jets)
1 Tub
2 toilets

9 cold ports 7 hot ports.
The hot manifold will be open leading back to the Navien boiler (ncb-240e) through a circulation pump (Taco smart sense)

With the showers having body jets (10 total) pressure drop is my greatest concern.

I am split between a 3/4" supply Line and a 1" supply Line. I would like to do a 1" to reduce any chances of pressure drop but will that put unnecessary work on the boiler with recirculation?

3/4" return for recirculation?

I realize the fixtures are all 1/2" or less but would running 3/4" to them assist pressure?
I can get a 7/9 port manifold with 3/4 propex outputs.

Also considering combining toilets/laundry cold outputs as pressure isn't of concern.

Only other fixture requirements is kitchen sink hot/cold which is close to boiler. Tee off before or after manifold?

Final question on the recirculation return to the Navian. Best to tee into the 3/4" DHW cold water inlet supply?

Sorry for the long post,just want to do this right while I have access to everything during remodel.

Thank you all in advance.