The warzone is a sort of 3 sided capture the flag zone, 2 sides trying to capture it while the 3rd (the borg) try to stop you.
Until you hit lvl20 it's fed against the borg, from lvl20 to lvl39 the KDF can enter and are supposed to try and beat the feds to the prize, but they usually just spend their time PKing feds that are out of their depth amongst the borg.
After lvl40 you stop getting the mission (at least that's when my current toon stopped getting it). so you only have 2 reasons to be in there, farming gear and PVP.
As to all of the players spawning at the same place, that's easy, the whole system is ****ed and has been since at least F2P which is when I started playing.
No, actually War Zone was messed up way before F2P. The spent more time fixing bugs than changing anything.