With any winch its a good idea to fit a
cut out so that you can disable it in a hurry if anything goes wrong, also it means you can disable it from fiddling fingers too.
Yes a split charge, if fitted with an over ride switch will enable you to isolate the primary battery and alternator etc so that you don't run the risk of leaving yourself un able to start. With mine I can run all the lights, all told its wired for 1560watts without the engine running and not flatten the starting battery or I can run say my in car PC and Ham radio all day ling parkes up etc and simiarly not flatten the battery. With a winch you might want to wnch through really deep water wiith the engine off (if you haven't got a snorkel) but still ant to restart at the other side. With an over ride you can connect or disconect the 2 batteries at will or allow the system to decide (ie when primary battery voltage reaches prest value).
For the small winch you should be ok with 185amp connectors (2hp - 127amp) and they should also be ok for jump leads too as that is a continous rating and a jump start should only need a quick burst of high current.
People use andeson plugs on defenders etc cos you can't get at the battery, on ours you can, don't see whats wrong with just a decent set of leads. Sure
fot the demountable winch you'll need a connector, you'll also need an isolator too - imagine what would happen if something got jammed in the end of the connector.
