Buying first "nice" watch, steel Datejust

[qwertyu]

Hi,

I'm in the market for a steel Datejust, my first nice watch. I've got some queries regarding this and would really appreciate your advice!

I'll buy a used one, and I've found a (to me, as a noob) surprisingly cheap Datejust (36 mm, 1996) with box but without papers. It's got some scratches on the clasp, but other than that it looks fine to my untrained eye. Costs about £2,500 in Norway, where I live (which I've heard is a relatively cheap country for watches). Does this sound like a decent deal in your opinion?

Would you say it's worth it to insure such a cheap but "nice" watch?

The seller of the specific watch I've been talking about lives in a small town without a Rolex AD. If he's serious (i.e. the watch is real) I assume he'd be willing to go to a non-AD with me to get the authenticity of the watch checked. Are non-ADs able to do this?

I travel a lot by plane, and I've heard about people with fake watches who get into a lot of trouble with customs (fined thousands of pounds). If the customs people ask me about the authenticity of my watch, I don't see how I can prove it's real without the Rolex certificate. Can I send the watch to the Rolex factory and get a certificate in that way?

My current watch is also a 36 mm dress watch. I'm satisfied with that size. My wrist circumference is around 20 cm or 7.85-7.90 cm. Is 36 mm considered to be small for this wrist? I used to own a cheap 40 mm watch, but I found it to be a little bit too big.

Thanks very much for any advice.