After playing some more on the MGDEV server I have this to say:
I hate auto-repair. If your base is starting to fall foul to an adv. goon, you may wish to grab defensive gear instead of keeping on repairing (say, if there are few to no defenders in your base). Auto-repair makes this incredibly difficult because you have to look at something that is undamaged to sell your ckit/ackit. I don't think holding down right-click (which stops the repair action) helps. While you technically could look at the roof (or make binds to look up, sell weapon, look down, buy weapon) to prevent this, it really should be unnecessary.
In general, I expect actions to be explicit, and if you ever have to explicitly stop an action, it should be something you are always doing, not something like repair. Auto-repair isn't really even that much of a convenience because you rarely start repairing something that you are not explicitly trying to repair (unless someone is glitch-building) and right-clicking is hardly difficult.
This sounds like a bug. I'll see what I can do to resolve it.
I think I like that you now gain progress toward stageup even if a turret or tube (mainly turret) since it seems more "fair". However I wonder if this will upset game balance/gameplay.
Well... that's sort of the idea

Firstly, I am worried that this will grant more incentive for the winning team to camp
I don't see this happening. Camping less useful now for various reasons, especially given that the enemy can now stageup by fighting your turrets rather than your players.
I am also worried that the newly nerfed rant will become even more of a hindrance because they now help stageup a *lot* and it might become too much of a better idea to stay dretch/basi/mara/shotgun rather than goon/tyrant/chainsuit. While this may not disturb the balance between alien/humans much, it will change the strategy quite a bit. Players may shy away from more advanced material because it not only gives more cash the enemy, but more stage points as well. It may also mean that if a tyrant/advgoon/luci/chainsuit rush is held off by a team with an inferior stage, staging up will become easier thus decreasing the momentum effect.
Both good things in my opinion. One of the things I love most about mgdev is how all classes remain useful at all stages of the game, and a team at stage 3 may well be composed of advanced basilisks for support, advanced marauders to zap at the tight defences, advanced dragoons to snipe and chomp what they can't manage, and a tyrant or two to mop up the human defence. It makes for a much more varied and interesting game.
And if a team of tyrants and advanced dragoons fails to take down a lower-staged human base, I think the humans should be rewarded for their defensive play.