How do I deploy a Sunderer?
Solution 1:
It's the B key. However, before you can deploy a Sunderer you have to unlock the certification to do so. The one you need is the Sunderer Advanced Mobile Station (S-AMS), which costs 50 cert points.
Don't forget to also equip the upgrade on the vehicle customization screen after unlocking it. You can only deploy when the Sunderer is stationary, on reasonably flat terrain. You can't deploy if there is already another Sunderer deployed nearby (the limit is on the order of 50 metres and shows up on the minimap).