First off I don't know what your game is but good luck with it.
What I expect from a first release:
...
Whereas I agree on these first and last points wholeheartedly, I just wanted to chime in on the opposite direction for the other two points.
Although having a plan is probably a good idea and I'm not advocating against it in any way, it is equally important to be flexible with your design and accepting of inevitable change.
By you (OP) saying "first release" it makes me assume that you plan to have many releases after that, and ultimately those are going to be more important than the first one. Don't hold on to mechanics if they're holding you back, be open to change and understand that game development is most successful as an iterative process.
Other than that, I personally like early releases to show off both depth and breadth as best as possible, so instead of focusing everything on one chunk of the game or spreading everything out to introduce as many features as early as possible, the game has a bit of both, giving a tease of depth for a single direction, but also demonstrating that the game will have other things as well. Unless your game is very linear, in which case that isn't relevant.