@trollol333
You can if you want to... at least the first two. EBF 3 you really should play before this one, just to get a feel for things. (Not to mention I'm pretty sure there is a direct reference to EBF 3's final boss somewhere in this...)
The best tower towards the lategame is the FoF missile tower.
The reason for this is the skill in the laser tree that increases damage and critical chance of all anti-air towers by 50%. the FoF missile tower is classed as anti-air. Add that to all the skills in the missile tree itself, and other damage bonuses... It is, by far, the most damaging tower in the game, and isn't even particularly slow to fire!