Wow thanks for the detailed feedback! We had some issues during development causing us to lose some time, so almost all UI stuff went to "Nice to have" instead of "Must have". For example, we wanted to add a crosshair, change how to switch between buildings instead of what we have now, also give hotel a way to switch directions, add more instructions etc. We also had our sound guy drop-out pretty early on so we really missed out there sadly :/
You can actually upgrade all the buildings but they are unlocked for that specific building only. That way you can for example choose the right tree with one fire station and the left tree with another. (My favourite to upgrade is Bowling Alley, it has some stupid funny upgrades near the end). We also had planned some more upgrades (our initial game idea was even that after X amount of waves everything you have build would combine into a giant Mech).
Anyway, thanks for the feedback! We'll probably make some improvements after the two weeks period has ended