Many thanks for your feedback!
"playable bug swarm faction when?": The plan is to expand the tutorial to a complete campaign - adding one "bug"-unit/building after the other. Eventually it should be a playable race. I already have the concepts for all the units, but I am pretty slow in creating the 3D-Models. So it will probably take a year ...
Regarding defensive buildings: I will keep your suggestions in mind. I am at the beginning of balancing things out. I am aiming for a good balance between rushes/teching-up/expanding. Up to now I only used different bots to try out different strategies and balance things. But in the future I will need some humans to try different strategies...