A lot of the events seemed staged but Hey thats entertainment.I am sure he made his fair share of money.

They signed all the documents and attended the closings, arranged insurance and dealt with the home owners association registrations.

I envisage doing everything through experienced professionals (who I find through personal connections) and paying well for it even in the early stages.

If both parties agree to this arrangement, what needs to be done legally and for tax purposes?

They will know from the line of work what is average.I have a tendency to advise aggressively; There is nothing wrong with arranging your affairs in a way to which you do not have to pay as much in income tax.

I'm in very initial stages of looking at a property that is non warrantable but obviously don't have all the cash to put up for it.

Add up the numbers and you'll find that, in most cases, you'll be able to make a lot more if you invest your money in money-makers and keep renting - plus, you'll be a lot more flexible and be able to freely upsize/downsize/otherwise alter your living arrangements by simply moving to another place.

I am just about to execute a lease renewal with this tenant - I'd like to potentially include a clause to assure the arrangement / responsibility is clear for the future.

This includes carrying costs during the rehab stage: insurance, property taxes, lawn care, utilities, etc.)2) A new HVAC system?

There is nothing wrong with that arrangement if that is how you (and your legal advisor, accountant, partners(?)