1) I'm sorry to disappoint you but 'Yours faithfully' is always at the end of a formal letter if the letter starts with 'Dear Sir/Madam'; 'Yours sincerely' when there is 'Dear Mr Smith/Ms Barbara King' at the beginning
2) that's right - 'talk on' = 'tell on'; as for 'future medical advances' - I prefer 'future advances in medical + science'; but your version is absolutely correct
3) 'the final date' is much the same as 'the closing date', especially in sport
a few + plural noun (this is a positive meaning), e.g.
A few people came to my birthday party.
Kilka osób przyszło na moje urodziny.
few + plural noun (this is a ngative meaning), e.g.
Few people came to my birthday party, unfortunately.
Niestety, niewiele osób przyszło na moje urodziny.
'we will be collected' - that was a sem-formal letter, which suggests using impersonal language, and the PASSIVE VOICE always introduces impersonal language