Squad leaders have three unlocks as well, and again, the first being the most essential - the Squad Beacon. Besides being a mobile spawn point himself, the Squad Leader can also drop this beacon, which does the same thing. Squad members can now plummet down to the battlefield near this beacon in "pods" - which can even kill unsuspecting vehicles and infantry if you land your pod directly on top of them.
Besides class- and squad-based unlocks, you'll also have the opportunity to gain global player abilities that go with you no matter which class you choose. The first two are the most vital: grenades and the extended sprint ability. Being able to run farther keeps you alive longer and is self-explanatory. Strikingly though, you won't receive grenades with any of the four basic class kits, and they have to be unlocked. 'Nades are clutch when defending or clearing the areas around flags and silos, and should be one of your very first unlocks.
The rule of grenades on the battlefield is: it's a shame to die with unused ones. So, even if you're surrounded and death is certain, take as many of those bastards with you as you can. Remember that right-clicking instead of left-clicking when your grenade is selected drops it at your feet instead of hurling it. This is perfect if someone is foolish enough to chase you around a corner.