shunter2005

Looks like an UFP A-60 actuator. Good actuator for surge and parts are plentiful most everywhere. You can buy either a new one if you don't want to mess with it, or buy all the parts you need and overhaul your current one. Parts would be the cheaper way to go if you decide to stay with surge brakes, but either way would work.

Question 1. No.
Question 2. Some people do and some don't. It's just a personal choice. Trailers with electric brakes are everywhere and drive thru rain and water all the time with them connected and don't have issues. When connected you have brakes at all times, even backing down the launch ramp.
Question 3. Lots of places to get UFP parts. You can get new surge or electric backing plates ready to go almost anywhere and they are pretty inexpensive. Etrailer, EasternMarine, Pacific Trailers just to name a few. If there is not a trailer place anywhere around you to get surge actuator parts, Pacific trailer and Bend trailers are both good choices for parts. I have ordered from both of them and they keep lots of parts on hand. I usually order from the place that has the cheapest price and best shipping rates that particular day. You will have to either buy a new coupler, either weld on or bolt on. You may be able to weld up the old actuator after you gut it, as well.