Correctly Installing LED Lighting

I'll bite for ya.

• No need to disconnect the battery. You don't turn breakers off when you change light bulbs in your house, do you? Well, you might... But I don't! These are the same concept. They can just drop in even if you're live. I'd recommend putting the vehicle in a situation where that light isn't getting current though just to hedge your bets.
• No need to disconnect the battery.
• You do not need CANBUS bulbs.
• I'm a little biased, but if you have the money buy Diode Dynamics bulbs and don't look back. Color accurate, reliable... If not, there's plenty of places to go for LED bulbs. I would recommend everything from one supplier though as that would be your best bet of getting color consistent bulbs.
• I would probably not recommend the brightest bulb that company offers for anything other than your dome light. I personally like a really bright dome light, but prefer a little more pedestrian amount of output from my map/vanity lights. You probably don't need as much light in those locations as you think.

Hope this helps