We will be renting cars in Greece mainland and islands. If anyone can please help explain how it works if there is an accident or something happens to car we rent?

Question is 1) : There is optional "FDW" full damage waiver coverage with Greece car rental companies that some companies state "0" deductible. Yet it appears they still want to put a 600+ euro credit card hold for damages even if I have this FDW coverage. So how exactly how does this work if there is damage to the auto? Do I still have to pay the car rental agency immediately when I return the car if there is damage? Then I file a claim with the optional FDW coverage company I paid for? OR Does the rental company let me go and handle any claims?

Question 2) Same applies WUG: Wheels, tires, underside & glass protect optional insurance? Some Greek rental companies offer. What happens if I buy this insurance and there is a claim?

Question 3) Please confirm if this is correct: In Greece "CDW" Collision Damage Waiver is REQUIRED by Greek Government for ALL car rentals. this CDW is Not optional and must be purchased when renting a car in Greece.
I have Primary coverage for accidents or damage with my credit card ONLY if I refuse the optional coverage by car rental company. However, I do understand that I will have to pay onsite rental company if there is damage and get reimbursed by my credit card company.

So, if I have to file a claim with Greek insurance companies’ same way I do my credit card company, obviously I will decline any Greek optional insurance. On the other hand, I am more than willing to purchase optional insurance coverage in Greece if they handle any auto claims and let me leave with the claimed ”0” deductible.

Thanks for your help and advice in advance