Try another map. If you choose a map for two players ["(2)"] you can't change that.

The problem is, i have no dropdown menu to select more players...   

I imagine you will need to pose the body mesh the way you want to with the armature and then import the props and combine them with the body mesh to make one mesh to print it. But, mind you, I'm no 3D printing expert.

It would be useful if in Ui we could see which bonuses were applied to some price/time

Yes, notifications are the best way to communicate stuff like this from the simulation to the GUI (and it works just as @phosit said). What kind of calculations? A "tick" in the GUI happens for each rendered frame, so the tick rate won't go up if you increase the sim rate (in fact, it'll probably go down a bit, since the game is busier with the simulation and has less time for rendering).