Welcome from Northern California! I can only help you with #4. No, you won’t need to use your water pump if you are hooked up to city water. I turn my pump off. Also I would suggest you get a water pressure regulator. I connect mine at the water source not at the trailer inlet. Again welcome ,you will find a lot of really nice folks here willing to help.
1984 gmc k1500 4x4 s/w/b. s/b 350,700r4,373 diff,.restored and upgraded. 2018 hummingbird Baja 16mrb,Yamaha ef2400ishc inverter.