PEX Fresh Water system/repipe questions -l ong

I have a series of questions about a potential repipe.
Background; I'm an ME with over 40 years of DIY experience. I've got a couple of older properties that are in need of repipes to replace failing galv steel systems. I grew with copper (CTS) systems & have experienced very good performance with them. No leaks, easy to make minor mods, etc. Part of me is thinking CTS because of my experience with it. But the idea of sweating all those joints in the crawlspace does not have me excited about this job. Based on comments from a few contractors I know, I'm think of making the jump to a PEX system. I've read a lot about PEX on the web & I've searched the groups but questions still remain.
Both properties are built over crawlspaces; one ranch style (~2000 ft^2), the other a 1 1/2 story.
The first project is the ranch style. I've got both design & installation/materials questions.
Installation / materials questions first:
Crimpers & expanders are mentioned when talking about PEX fittings. Which are used/recommended for fresh water systems? The hand expander costs about 2x more than the comparable crimper. The hand expander looks slower & potentially more tiring than a crimper but might work better in close quarters. The battery expander looks pretty cool but rather spendy for only a few jobs. Bras or EPS fittings? My "old school" self leans towards brass.
I guess the next questions are more design "style" questions.
Other than the failing steel pipe, the ranch also has the "shower far from the water heater issue" (~80ft) which is amplified by the feeble flow thru the ancient steel pipe. So I'm thinking about a timer run hot water loop with repipe to give some really nice performance. Since I'm repiping anyway it will be a little more work to add the hot water return line.
But the hot water loop seems inconsistent with the manifold installation concept unless the hot water mainfold is near the major bathrooms? (two co-located, back to back bathrooms, ~80 ft from WH).
Hot water "home runs" from the water heater area (in laundry room, near kitchen) to every bathroom hot water need (two sinks, two showers, one tub) seems wasteful of PEX tube & don't seem to solve the waiting for hot water issue?
Relocating the WH is not an option & I'm not up for doing the tankless thing at the bathroom point of use.
I was thinking that a remote located HW manifold much closer to the bathrooms might be the solution. I could tear open a hallway wall next to the bathroom & install the hot water manifold there. Or give up another 3ft or so & put it in an existing closet across the hall. The remote manifold could be served by a timer controlled hot water loop thus elimininating about 75% (60' out of 80') of the hot water wait time.
Now more questions;
IF the remote hot water manifold is a good idea, how large a tube to supply it? 1/2? 3/4? Max hot water demand from bathrooms would be two showers at a time & MAYBE a sink. About 4gpm max hot water demand? With an 80 ft run of 1/2" PEx that would be about 16psi pressure drop. Sounds like 1/2" could do it? Or just bite the bullet & go to 3/4" to serve the mainfold & have a ???" run on hot water retun loop?
In SoCal does /should a PEX hot water loop be insulated? Overkill? Not needed?
Thanks for taking a look at this. Hopefully replies will get me off TDC & get this project going. :)
cheers Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

Current home is plastic piping. The shower pressure SUCKS they used 1/2", guessing less that 40 feet. I do not use the tubs often so the time they take to fill is not really relevant, it does take some time. Outside rear water pressure sucks as well. I have to use my 120v pressure washer if I want any pressure at all.
I did adjust the pressure regulator up to 45 pounds, max for this type of pipe.
Forget the hot water loop, just buy a hot water pump. Pulls hot water from the existing line and pumps it back into the cold water pipe. If your staying for any length of time insulate all of the hot water pipes to areas that will be using a lot of hot water. Example I would not do the clothes washer line as I do not use hot water wash's, just warm. Would do the kitchen sink as the dish washer uses a fair amount of hot water and hotter is better for sanitizing.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.