Hi, I'm a pretty good DIYer in most everything except for plumbing so am looking for any info. anyone can offer. I did put in a lawn sprinkler system several years ago and remember some stuff about gpm and pressure stuff but its been while.

I'm remodeling my master bath which had an ugly fiberglass shower stall, that I have ripped out. The right side of the stall was a half wall that I want to replace with glass block. The problem though is that the plumbing for the shower ran through that wall. I would like to put in an overhead rain-type shower head, a handheld shower massager that will be located on the left side wall and possibly even a couple body sprayers.

For ease of installation, I have run PEX pipe beneath the floor joists over to the wall on the left side. Couple questions on PEX:
1. Do I need to secure the pex to the joists or is it OK to just let it hang there?
2. Does the pex need to be supported/reinforced where it makes a 90 degree turn?
3. Are you even allowed to have it run like that or should I keep the PEX running straight and use fittings to make the turns?
4. Do I need to convert back to copper in the wall to avoid vibration chatter?
5. Anything else I should be sure to do/not to do?

Other questions:
1. In adding another shower head and possibly body jets, i assume this is similar to my lawn system in that I need to figure out the available volume and then stay within that range with all the fixtures?
2. Can I just T off the PEX pipe to run lines to each fixture?

In my ignorance I fear I am missing some probably huge things. Any help is most appreciated.
Thanks,
Scott