Re: Will they hire me?
A nurse's license opens many doors. This is only partly because a lot of places are desperate for nurses. Another part is that passing nursing school says a lot about you. It's no easy feat, and the people who hire nurses are well aware of that. It can reasonably be assumed that anyone who graduates and passes NCLEX is reasonably bright and reasonably hard-working. A rare few may slip through that make you wonder--but even they will probably get hired, somewhere...
Don't fret over your presentation. My NM gets as nervous doing job interviews as if she were the one applying for the job. My Director manages to make an inadvertant double entendre at nearly every staff meeting. In many ways, social skills are an important part of nursing, but being cool has very little to do with it. Even if you bungled your presentation as badly as you think (unlikely, but possible) the difference between a demonstration and actual practice is just enormous. A much more telling question would be how you handled the debaucle--did you lose your temper? freak out? quit?
An appalling lot of nursing comes down to being able to stay calm (at least outwardly) and keep plugging even when everything is going to crap around you. There's a lot more to it than that, of course, but it's entirely possible that the nurses who observed you were impressed that you managed to get through it with reasonable aplomb.