2. yes, there is ticketmaster.com in USA
3. In USA everything is seated, there is no generel admission area
4. There are seats from front to back so it's first of all a matter of how many money you are willing to spend. Front row seats costs up to 1500 Dollars.
5. There are busses from NY to NJ, so no problem to get there. But you should rent a car in NJ since they don't have a public transportation like we know it from England or Germany. Even in front of the arenas and stadiums there aren't busses or even taxis because in US everyone comes by his own car to the shows (I experienced this in Giants a couple of years back, gladly I got a phone No. of a taxi company).