I've got the winch mounted and it's wired up. Have a wired Warn remote. Winch sounds like it's running ok, but haven't operated it under any kind of load as yet (read the vinyl Warn covers were allegedly good at keeping rain out, but tended to trap moisture on the inside -- the vinyl winch cover doesn't "breath" like a good car cover. So, got the neoprene cover; it doesn't do much to block external moisture, but does breath some and presumably blocks UV.
Was planning to install a MKVIII electric fan -- it'll be looking to connect directly to the battery, I guess. If I get a 4 channel amp, that's apparently going to have to be wired to the battery also.
Do have a 210 amp alternator installed. Haven't searched around on this question:
What's the point where you install a second battery? Daytime on-road driving, I'd expect the electric fan and amp to draw power. Nighttime it could be electric fan, amp, and headlights...