1. Each continent is 64 square kilometers and can hold up to 2,000 players at once. That cap could go up or down during beta, once they see how the lag works with tons of people.
2. As you can see from the image at the top with the hexagon grid system, everyone won't be at a single place. Each of those hexagon groupings is BIGGER than a multiplayer map in today's shooters. (Call of Duty, Battlefield, Tribes, etc...) Players will be spread across the "front lines", and some will be going behind enemy lines to disrupt their supply and benefits.
3. There will be 3 continents at launch: Indar (which is the continent we've been seeing in all the videos), Esamir, and Amerish. The other 2 continent's concept art:
Esamir: http://www.planetside-universe.com/medi ... 574858.jpg
Amerish: http://www.planetside-universe.com/medi ... b5e5f2.jpg
4. One thing I recently pointed out to a friend is you don't have to be a part of the "zerg" if you don't want to. The game supports real life tactics that would make Sun Tzu proud. Because all of your opponents are people, they can succumb to same tactics real life military commanders use. Distractions, feints, flanking, shock an awe, scorched earth, etc...
5. Lastly, and I won't sugar coat this, you will get shot A LOT. In a purely PvP game, you can't wait for devs to nerf something because you think "it's too hard". Adapt to changing situations and get better. Knowing your capabilities and the capabilities of your enemies will save your ass.