Hi Ohno,
I can't answer all your questions, but I'll have a go at some of them.
1) Realy don't know about credit union stuff, particularly if you are deducted at source. One of the other experts will probably help you there.
2) Most advisors will tell you to stop paying your creditors once you have started on the road towards the IVA. You will get phone calls and letters, but you will be able to build up a little contigency.
3) I think your car payments will be ok, and may even be paid before you have an IVA approved.
4) You need to open a new bank account as soon as possible with a bank that is not one of your creditors. Move all your direct debits and standing orders and salary across to the new one. The Co-op and Nationwide are two good ones.
5) When you have paid all your essential bills (mortgage, utilities, food etc), how much disposable income do you have left.
Hope that helps
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley.
http://kallis3.blogs.iva.co.uk