I cannot answer this question as I am running a RazBerry Shield. AFAIK the license is included there so that I don’t have to do anything to add it manually. Perhaps you should ask the designer of ZWay, because that is a “problem” with ZWay itself.
Selecting your Zway-server thing and editing it you need to give you password of the Zway user. This mostly should be the admin user. So what user do you use to go to http://zwayserver-IP:8083/ ?
I cannot help you with the third question. But perhaps it goes away after fixing the other questions?