1 : I thought of something like this, however, It would likely be innately imbalanced, and make it so that unless there are drones with the ability to one-hit shields, the creeper will be completely unable to gain ground. So I say no to this idea, as much as I want it, because it would unbalance the game. Build shields behind the shields that are going to fail instead.
Ridiculously overpowered. If you still want to repair a shield, you kill/convert the creeper around it, destroy it, then rebuild it.
2. Subcell movement - You can move to every 1/9th of a cell. To use this though it would be you hold Ctrl (or command) for more percise movement.
The game is not and never was intended to work in that way, and implementing it would require completely redoing a wide swath of code to allow for it.
3. I like it, I would really like to be able to do this, and I have the same issue. I give my 100% support for this.
Selecting non-movable structures is a bit of a pain to implement right now. There are things scattered through the code that assume only movable units can be selected. But, I know what you are saying. I'll likely have to wait on implementing this since I would like for a new update to come out pretty soon with code maps. Then I will immediately plunge into custom map support, and the real insanity will start Smiley
In that latter category: I propose to make a waypoint functionality (say with the alt key) that allows you to define intermediate locations in the case you want to override the standard pathfinding algorithm.
Now this is something I would really like to have if it could reasonably be implemented.