Does a thesis paper have to actually solve the problem posed or only show potential ways to solve it?

What level are you? Doctoral students typically do experiments. Master's students might- undergraduates don't usually. And you can't do a medical experiment on people without a very extensive review process. What you CAN do is survey people (it still needs to be approved by your institutional review board, but the process is a lot easier.) Really, only your advisor or the teacher of your class, if this is for a class, can answer your question. 

You don’t have to argue for the viability of a strategy but you have to establish that an ongoing strategy is implemented and that it entails various things 

That depends on what is required of your particular program.  You should talk to your advisor about this.  My own thesis and dissertation had to involve human subjects research, so I had to collect data from volunteer participants and analyze it. A theoretical paper or a proposal was not sufficient.

this is a question for your thesis advisor -- answer may differ by institution and type of program

hat depends  on the thesis project. I analyz ed and interpreted one  ou   5 sateltolite images for remote sensing thesis for an M.S. in geology. Yes, I did have to do field truthing in the field. Yes, I did have to orally defend my thesis. I passed. 

You really need to discuss this with your thesis person. I suspect you have not written or orally defended your thesis proposal yet. Different departments and schools do meters theses or undergraduate theses differently.