I'm no doctor, but from what I know, is AF  a specific diagnosis - or rather four different ones according to which category it belongs to.
While palpitations is a much broader concept which might include AF but also ectopic beats and other sensations of the heart.

I would guess that a holter has a chance of catching whatever it is. That is, if you have a "bout" while wearing the monitor.

Blood pressure is always up and down!

Is AF dangerous? From what I have read and remembered certain categories/certain amounts of AF increases the risk of blod clots in the brain because a lot of AF might cause a "whipping" of the blood, causing clots. But I think you have to have a lot of these "runs" before it gets dangerous.

You must ask your doctor and persist until you understand!

Best of luck.