Okay, my bad.
Played a bit more and...
You really have to try different strategies with towers.
I tried to add magic tower to my mix and freezing started to work. They are really good against bosses.
Moreover, magic tower have larger range compare to stone, so it can hit enemies that reached the base.
About #9. There is no button, but if you read (i didnt before) you know how to jump back to menu :D
Thanks again for the game. I think it's great that game can offer so many options to play and explore.