Used to convert your 12 volt DC car power to allow you to run items that normally run on regular house 115 volt AC. Home TV's, DVDs, etc. most anything with a normal houseplug....if I understand your question. can be used to run a home amp in a car...not the other way around. Tons of them out there and available most anywhere now.
Yup. Went on a road trip with a friend when i was a kid from maine to new york, they took the minivan, emptied out the back seats, threw down a few blankets, and set up the nintendo 64 and 30 something inch tv in the back. Mario cart all the way to NY. Those inverters are nice if you get a quality one. I've burned through one by accident by overloading it, it didnt function properly and ended up smoking... Don't get a cheap knockoff if your going to be running 7000W from it. That's an insane ammount of power for something in your car. You could run a damn refrigerator on that.
30" TV just sitting in the van with kids going 70mph on a freeway... Accident would have been a mess.
Average household fridge probably peaks at 700W, depending on a size, of course. PC with an LCD screen is about 300-400W, so at 3500W continuous you can run 10 PCs. On the other hand I have no idea how are they planning to make a 3500W inverter function in a normal car - aren't alternators 100A or so? 12V x 100A = 1200W. There is no way the car can push all 3500W...