Can somebody explain Support skill upgrades?

Can someone run down the 3 levels of the 4 support skill upgrades? I don't undrestand some of them. I especially don't understand what the bottom grey skill upgrade does. Does it make you heal more?

Thanks for any help. I love the game, but some of the in-game descriptions are a little vague.

Hack: Level 2- Increases turret range. Level 3- Increases turret fire rate.

Firebase: Level 2- increases fire rate? Level 3- Adds heal aura

Airstrike: Level 2- 2 airstrikes max Level 3- 3 airstrikes max

Passive: Level 2: Adds aura to bots that gives them more hp and rate of fire. Level 3: Increases support's max hp.

That helps a lot. Thanks!

Just a heads up when you press up on the d-pad and select a skill in the top right hand corner it will tell you what the next upgrade does. Just for future reference.