Looking for a Joint Venture

I am a wordpress newbie. I am in a position where I can sell bucketloads of subscriptions to professional clients that want a website. However, setting the system up (domain registration + individual site setup with several options – like single user, multi user, membership site etc.), securing it, backing it up and supporting the clients is quite beyond me.

Do you have any advice on how I can proceed? How can I find a reliable partner for a long-term relationship? How should the deal be structured – Initial setup fee + % of monthly profit, or a flat fee for each client that signs up + flat monthly fee for each client? How can I ensure that my customers do not suffer poor service because the partner loses interest?

Are there established businesses that already provide this sort of reliable service. If there are, what are your recommendations? Basically, I want to market the service and get a reliable expert deal with the tech side.

I know that this is a very general question, but would be grateful for your advice.

Regards

Mohan Reddy