Ok, we do these all day every day at work. TO answer your three questions:

No, I haven't had one. But I've been present for plenty and recovered plenty of patients!

Yes you need a referral. I can probably recomend someone for you.

Technically, you are not knocked out. You are given what is considered a "light" sedation. Some people are more "asleep" than others due to how their body responds to the drugs. Typically, most places use midazolam and propofol for sedation. You will not be aware of is happening nor remember what happens, in fact 80% of people don't recall anything from the remainder of the day.

Any other questions, feel free to ask.

MG