Sorry for my late response, I've been away on business.
1. It is a "Radio Shack 12 VDC to 115 VAC High-Efficeincy 220 Watt Portable Power Inverter". It also has 04A01 on the back.
2. One plug, but I assume it would be safe to use a 'multiple plug adapter'. As long as you're not running over 220 Watts.
3. Using it while the engine running is the best bet. As I understand, you are constantly recharging your battery while your engine is running. I have used it with my GPS and notebook from Erie, PA to Indianapolis, IN (almost 8 hours) with no problem. When I visit any town on sales calls, I use it with my GPS and notebook. When I turn off my engine to visit an industrail plant (or gas station), I'll keep my notebook and GPS on. As long as I'm not in there for a couple hours everything is fine. Once I start driving again my car battery recharges.
I'm sure there is a little shortage in battery life with my method of not turning off the notebook, but it's too convenient not to.
OK, enough rambling. . .I've had a couple cold ones and it's late. Therefore, however, please do note: execuse the spelling errors and lengthy message. bye bye, ouzome