Hi Welcome back to the forum Marie241179,
I will answer your point in your order.
1. A F and F is a full and final offer normally made if you need to end your IVA early, some people will offer a lunp sum instead of payments for 5 years. Do not worry you will not need to find a lump sum
2. You are still bound by the IVA until you receive your certificate, for windfalls etc, just dont win the Lottery until after you have your certificate
3. When you have made you final payment I would riung your supervisor to confirm and they should advise you to cancel you DD
4. Some companies do a final review at the end just to mop up any uplift payments for overtime etc
5. I would say it is extremely unlikely to fail now as you have complied with everything you were asked to do.
Relax and enjoy being at the end of 5 long years, and start planning that holiday.
(Edited to correct spelling mistakes)
If life is what you make it, I must have been in a strange mood when I made mine