Piping/sizing question

Been awhile. I am finally in my Amish house and getting started in getting some services installed. Because of the location of the cistern/well the pressure tank will be on one side of the basement and the water heater and most of the requiremnts (bathroom/kitchen) will be on the other side of the basement (~20-25feet). I am planning on sending the water from the P-tank over to the other side then have a distribution point for all the feeds (PEX manifold). Here are a couple line size questions:
1. What size line from the P-Tank to the manifold (1"?) PEX or PVC?
2. Tankless water heater has 3/4NPT in so can I build a 3/4" manifold on the output side to feed hot water out to the shower, sink, kitchen, etc?
3. Would I feed the shower and sinks off seperate 1/2 lines or send a 3/4 inch suppy there then tap off that with 1/2' pex.
4 Build the same thing for the cold water piping?

Thanks in advance.

I would run 1" over and reduce to 3/4" for the water heater. If your 1" line goes past any fixtures (cold) you can tee off it for them rather than go backwards later.

Can't use PVC for water supply inside the house. Use 1" PEX, CPVC or 3/4" copper.

Gary's right about the PVC, I missed that

My dad used to say, "A blind sow can find an acorn once in awhile!" I guess a dumb DIYer can find something others have missed occasionally.

Sows like acorns? I thought it was a "blind squirrel".

Guess it depends on what part of the country you're in.

Thanks Gent's!