This is my second year for using 5 of these units and last year the batteries lasted the entire season in all of the timers.
That is kind of a pain, I had to take needle nose pliers and pull pretty hard and then the battery pack pops out. It felt like I might break it but I didn't have any problems, it's just in there snug. Pretty sad that the directions don't explain that.
Yes, you can set up each zone for up to 4 times per day.
What you describe is very doable. Make sure that you program very carefully and you should be fine.
It’s made to be outside.
less thn 125
Yes, if your state or local plumbing code requires one. California requires one, and I'm using this timer for drip irrigation, so I installed the Rain Bird 3/4 in. FHT Backflow Preventer with 150 Mesh Filter (SKU 883952) on my backyard hose bib.
Yes. Just use as many outlets as you need.
If you are trying to prevent backflow into your house, you will be fine. Same goes for the pressure regulator.
Manufacture makes recommendations for this.