Tip: consider creating your session in a Room, for more stable start links that are not opened accidentally.
Must be a multiple of 1
Since workers can return an assignment or drop out, some "spare" participants will be created: the oTree session will have 2 times more participant objects than the number you enter here.
You can make more properties configurable by adding them to your session config in settings.py.
One player decides how to divide a certain amount between himself and the other player. See: Kahneman, Daniel, Jack L. Knetsch, and Richard H. Thaler. "Fairness and the assumptions of economics." Journal of business (1986): S285-S300.