1) I try to seperate how zorro is licensed: If I have two computer, one for algo development and another one for live trading, do I have to buy two "Zorro S" licenses or one?
Assuming you're a natural person and not a business, one license is enough.
"A personal Zorro S license, issued to a natural person, allows multiple Zorro installations on an unlimited number of computers or servers when only the licensee has access to them. Corporations need one Zorro S license per installation or per user ("seat"); please contact us for license bundles."
https://zorro-project.com/manual/en/restrictions.htm2) IB plugin: is it possible to connect to IB with "Zorro free" to an IB demo account Port 7497?
Yes because demo accounts begin with a 'D':
"The IB plugin included with the free Zorro version supports paper trading accounts that begin with the letter "D". A plugin for real accounts is included in Zorro S."
https://zorro-project.com/manual/en/ib.htm
