Newbie need advice

[nycdiva]

I just recently joined the forum. I am very new to the world of Rolex and my head is spinning. I went to the Rolex store yesterday and fell in love with a TT yellow gold SS mid size datejust with jubilee bracelet with MOP dial and diamond marker and a full or 24 diamond bezel. The full diamond bezel one was 20+k, and the 24 diamond bezel was 16+k.
I was hoping to find the watch I want preowned, but that seems even harder to do. My questions for you all are the following:
1. Are Rolex factory bezels worth it? What is the resale value of them?
2. Is the MOP dial worth the extra $$$$?
3. If I come across the EXACT watch I am looking for preowned, will it be 20% less than a new one or 50% less?
4. If I come across a preowned midsz TT DJ with MOP dial and diamond markers, will I be able to find a factory bezel at a later date?
5. Can most of you tell the difference between a factory bezel or a custom bezel?
Thanks for your help!!!