Results Presented in Conferences and Their Publication
On 1, if you present something at a conference, there will be witnesses that you presented it there, and you will have documentation of your work products on your computer, in your lab notebooks, etc. If someone does take your work from your talk and try to publish it, you can work with the journal editor when you discover it to prove that whoever it was stole it from you and have the publication pulled so that you can publish instead. You can also contact the employer of the stealer and have disciplinary procedures started against them. Stealing your work is not outright theft in a legal sense, but it is serious academic misconduct, and shouldn't be taken lightly by anyone.

Also, this isn't dangerous. As far as I know, this kind of stealing basically never happens. That being said, if you want to protect yourself even more, write up you results into a paper draft and get it submitted to a journal ASAP. If the work is under review, then you've got a lot more protection from having your work stolen.

As to 2, "I hear" is a bad standard to base your decisions on. Contact the organizers of this conference and ask for their advice. You might even link to the conference so that we can help you figure out what's going on.