Water service. OK, now I need some advice......

[Nukedaddy]

I got away from plumbing with the tools about the same time that PEX started becoming popular. I have a couple of questions that when answered will help me make some decisions.
I intend to use PEX white tubing as the supply coming in from the meter, but I want a branch underground to go to a potting shed for my wife. Am I OK to use the regular insert fittings underground or should I stick with red brass compression as if it was copper tube?
I want to put all my PEX that is under slab in conduit that would allow replacement. 1 1/4 PEX would do but is expensive. Regular black PE would, and the corrugated blue “smurf tube” conduit would do. What does everyone else use?
Last, I want the best flow characteristics I can get. I think that the Wirsbo insert fitting system with the PEX rings and expansion tool may have the biggest ID in their fittings. Am I right?
I know the OD grabbing fittings like Sharkbites do not reduce ID in fittings but are much more expensive and I just don’t really like the idea of putting them inside of closed walls.
So the question is....what brand or type PEX system has the least restrictive fitting dimensions?

Oh, and one more! Are there any really compelling reasons to use the copper or brass insert fittings over the plastic ones? Are the plastic fittings made of the same PEX resin as the pipe? Are there good reasons to use plastic fittings over copper?

And another... What is the most popular piping “style” with PEX? I see benefits using the headers and a “homerun” to each fixture except for the long hot water waits. Smaller headers near each fixture group sounds better, maybe with hot water recirc and insulated hot piping?
Conventional piping strategies minimize total piping length but triple the number of fittings. And makes the use of pressure balanced shower valves important.

I know there is a lot here to answer, but this is a good one stop shop when it comes to getting experienced opinion!

KarlwithaK

 

[JohnCT]

So the question is....what brand or type PEX system has the least restrictive fitting dimensions?

That part is easy: expansion type. Since the pipe is measured by it's ID, any fitting that slides into the pipe will reduce the flow. With expansion, the loss of flow is reduced as the fitting is larger than the resting ID of the PEX. But even the expansion fitting reduces flow somewhat because the fitting isn't quite as large as the OD of the unexpanded PEX. But the short answer is expanded PEX A such as Uponor.