1. It does not happen often that researchers try to steal ideas. The risk may be higher if you are working on a very hot and competitive topic. How to protect yourself: try to publish your result somewhere by submitting a journal paper in the near future would be a good idea.

Besides, the risk is not just that someone may steal your work, but that someone could do something similar but different that provides better results. Let say for example that some researchers see your method A at the conference. Then they publish alternative method B before you publish method A in the journal and method B works better than your method A. In that case, it may then be hard to publish your method "A" This is why, it is important to not wait too much before you publish your work. This is true if you work on a competitive topic. On some topics, you need to publish very quickly otherwise other researchers will publish ideas before you.

2. Contact the conference organizers. The % depends on the conference/journals where you publish. I have ever seen some venues/journals asking for 30%, 40% or 50% new content. It all depends. You need to ask if it is not indicated on the website.

1. It does not happen often that researchers try to steal ideas. The risk may be higher if you are working on a very hot and competitive topic. How to protect yourself: try to publish your result somewhere by submitting a journal paper in the near future would be a good idea.

Besides, the risk is not just that someone may steal your work, but that someone could do something similar but different that provides better results. Let say for example that some researchers see your method A at the conference that is unpublished. Then they publish alternative method B before you publish method A in ajournal and method B works better than your method A. In that case, it may then be hard to publish your method "A" This is why, it is important to not wait too much before you publish your work. This is true if you work on a competitive topic. On some topics, you need to publish very quickly otherwise other researchers will publish ideas before you.

2. Contact the conference organizers. The % depends on the conference/journals where you publish. I have ever seen some venues/journals asking for 30%, 40% or 50% new content. It all depends. You need to ask if it is not indicated on the website.