1) the union is a male threaded end that threads into the female threads on the Ultima head unit. The other end is female slip.
2) use thicker tape like the grey mighty stuff. It will match your plumbing better. Do not use any type of putty or cement or it voids the warranty. Use on roll per union. That will feel like too much. It isn’t and you may end up using a whole roll to stop a leak after it’s running anyway.
3) You can swap out the white for grey schedule 80 no problem. Order a male thread x male spigot from BRS in 1.5” and it will keep your plumbing clean and not as bulky.
jsodwi does some killer work! That looks great
For the union did you mean slip x male spigot? Doesn’t look like BRS has such unions. Can I just do a slip x male thread and then use a threaded nipple to connect to the ultima?