Air bags can be a great addition. They are designed to restore ride height and increase load capacity, but they will
not increase GVWR. They do not help with sway control, as a matter of fact they can make sway much worse, especially if the right & left bags are plumbed together. If you need to reduce sway then you should look into a larger rear anti-sway bar or (depending upon your truck) upgrading your overload-spring bump stops (see:
StableLoad)Note that air bags can cause harsh ride quality, especially at higer pressures. This is due to their rapidly rising spring rate. This can be somewhat overcome with the addition of ping tanks.
I use
Firestone RideRite airbags with an in-cab control system, and I am very happy with them! But if/when I replace mine I will be going with
PacBrake bags (IMO, the 'best brand').
Cheers
-Mark