what documents are needed to open a bank account in turkey, i.e. proofs of identity etc.
Tax number & passport.
How long the whole process takes from getting an insurance number to time at the bank.
As long as it takes you to queue in the bank, Tax number issued while you wait at the main Post Office.
What banks are best in the Fethyie area.
Subjective, personal choice.
What exactly are the interset rates for normal and investment accounts.
Ask on the day you are ready to sign up, changes daily & currently going down, sadly, but currently "up to" 9% on a monthly account.