Can you advise me on the winning formula for job-hunting/ interviews?

I’ve worked more or less since the age of 14. (I’m 42.5 now) For about 19 years I ran my own business, I was employed for 4 years in the same company up to 2003.
In 2003 I was diagnosed with the Big “C” and I had to give up work. At the time I was a Manager.
I finally got the all-clear in 2008 after another scare and I now feel I am ready to get back into full time employment.

Thing is, My C.V. (Resume) kind looks a wee bit threadbare from 2003.
Even when not working I helped my wife run her Tattoo / Piercing studio, I helped create and run local websites for Recycling, Local pet club, chat group, also fundraising for local charities. I run my wife’s website, I’ve also been involved in helping her in her training of staff, with health and safety, UK Legislation etc.
I intend to apply for supervisory / senior positions within the industry I was in but wondered a few things:

It’s been a while since I’ve had an interview, tried to sell myself as it were, what tips can you give me?
Would you advise I put the volunteer and unpaid work onto my C.V. (Resume)?
I’m totally over my illness now and want to kind of make this point, how much detail should I give? how would you explain that to a potential employer? or would you put it in your C.V. (resume)?
What tips do you have for regaining confidence in the workplace (and in ones-self)?
What other advice or nuggets of wisdom can you pop my way?
What’s a winning interview technique? (is there such a thing?)

Thanks for listening.