Tier 1 Talent Visa - Please Help

Hello everyone and I need your help! I cannot find a lot of information about Tier 1 Talent visa in dentistry and medicine.
I have PhD in dentistry, worked as a dentist 11 years. I'm in the UK on spouse visa, but I want apply for this type of visa. I'll get job now at the university as honorary lecturer, it means without salary. I can get recimmendation letters from the UK university peofessors. Do I need anything else?
What do you think do I need to apply for Exeptional promise or Exeptional talent. I've seen that we have ro pay health insurance...but I don't know how many years do we have to choose.
I know that I have to apply for visa from my country. But, it is possible that I apply for Stage 1 from the UK, and then Stage 2 from my country?
If anybody helo me with morw information I'd be so thankful!