I don't know anything about questions 1 and 3, but for #4, you definitely need a regulator to control the pressure to the autofill. My Poolmiser autofill indicates no more than 40 psi (I think) in the instructions. I'd also be surprised if the hose bib is rated for full pressure also. Might verify that as well.
For #2 - I used these glands -
https://smile.amazon.com/gp/product/B07S9ZTF18/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Then I threaded the gland into the 2 x 1/2" Tee, and installed the standard temp sensor into that. Been going on about 2 years with no issues. You can see it right in front of the filter in the pic here.
View attachment 404104
--Jeff