Hello Rupert,
A lot of the answers to your questions could really only be answered once a mortgage-broker had a very good understanding of your personal circumstances.
For example a mortgage broker would need to understand the status and amount of your current credit (within the DMP) to weigh up whether you'd be better advised to seek to buy pre or post IVA acceptance. The status of the credit in the DMP may also have an effect on the amount that you're able to borrow compared to the amount that you could borrow once in an IVA.
Given the integrated nature between various debt solutions and mortgage options I do think it's important that you choose to speak to a mortgage broker well-versed in these issues.
I'd be very pleased to talk it through with you as I'm sure would Tony (Welshboy) and Mike (Mikebdomain) who also regularly post on this site. All of our contact details are available in the profiles section or via the web-links.
Andrew Graveson
Mortgage Broker & Bright Oak Debt Management
andrew@brightoak.co.uk
www.brightoak.co.uk