New Year's Eve is always a "hard ticket" event (meaning you have to purchase a seperate ticket to get in) and the clubs and access to the main stage concert will be available only to ticket holders...and yes, it is wall-to-wall people every year. (BTW, Hard Rock, Nascar Grill and NBA City are not part of the ticketed event).
The Universal web site will probably have ticket information for NYE some time in September that will list the prices and headline entertainment schedule for the event.