Screw eyes that are screwed in counterclockwise

That is how it should work. The drill is designed so that less pressure on the trigger means less power to the drill. It could damage the driver if you were to keep it in that state of trying to turn and failing for an extremely extended period, but not if its momentary like you describe.

In short - good question but you're worrying too much. :)

Oh - yes - by the way - actually this is what it was designed for - exactly so. It's designed to apply torque to bolts and screws and drill bits.

A few options, in no particular order:

Drill pilot hole first

Take the batten off the wall, drill pilot hole, replace. Then you can use whatever size screw is necessary.

Use a flexible drill shaft

These plug into an existing drill and let you get into tight places.

Use double-sided tape or adhesive

Not as strong, but depending on the application may be an easy way to accomplish the goal of preventing shelves from coming out

Use an angle bracket

Use a couple small angle brackets to drill into the bottom of the shelf.