Thanks for the feedback and I'm happy to hear you enjoyed the game.
1. We already have this implemented for the next release
2. This also something that will be changed in the next release. And we'll also make it so that enemy layouts change drastically every ~5 stages so that it's important to change the strategy every now and then, but the strategy is useful for longer than a single stage.
3. Structures and World are a bit of a bait, as they are not yet available. We'll add info about that in the future releases to avoid misunderstandings.
We also reworked how the placement of units work to allow "overlapping". You can check the video on discord in #updates if you are interested.