1. i assume you mean your LED for the external indication light, i dont where you would connect it on a 4QD (although there will be somewhere on it for them, might say in instructions). but it can be connected anywhere in the main power circuit.

2. if its the blade fuse holder in cars etc, then i doubt it can take the current for a heavyweight. the best thing to use is a anderson connector, available from Technobots (but if your in a hurry, as hes closed this week, then they can be got from RS)

3. it will charge it but blowing a battery up will depend on type of battery and charger. what type of charger is it?

4. no.