Paul, these are tricky areas, and I don't know if anyone on WW knows the answers, but a few things do occur to me. Apologies if you've thought of any of it already!
It sounds as if you need a ghost writer: a professional writer who takes your story, and with you, gets it down on paper and into shape. Then you can either try to get an agent to sell the concept of the book to publishers, or approach publishers direct, or write the book together and then go after an agent or publisher. I don't know which would be sensible in your case, but the ghost may.
In the nature of things, ghost writers are invisible, but they can be found. The Society of Authors can put you in touch with members who are professional ghost writer:
http://www.societyofauthors.net/soa/faqs.php4?faqid=8
which also has a link to the Society's 'Quick Guides', including the one about ghostwriters and collaborative contracts. I'm not sure how fees and things work, but the guide will tell you. Any ghost is going to be happy to discuss the project for free, while you both find if you're well suited to each other, which is very important.
As a member your ghost will also have access to the Society's advice and support, and I'm sure they would answer some of your queries too.
There's nothing to stop you publishing under a pseudonym, or anonymously, though obviously there will be people in the trade who'll need to know who you really are. The legal questions I don't know about; you may need to pay for specialist legal advice, and the Society (quite a few of whom are lawyers themselves) may be able to refer you to the right specialist.
Hope that helps.
Emma