Don, I am a Contractor and Investor from Philly Suburbs..I would find out if all 3 guys are skilled mechanics or a mix of mechanics and laborers.

If you're doing a turnaround project with greater uncertainty and skill required to achieve the upside that should command a premium when determining the yield required on the equity.

A wood-worker friend- of-mine, who makes stunning projects, said it right, "I don't have any special skills, I just buy the right tools."

I can't imagine that a contractor would bring more to the table as a partner than as an employee/contractor, so bringing him in as a partner is just diluting your control and your profits.What happens when you realize that the contractor isn't very skilled?

Since I haven't had to deal with a meth lab house (amazingly, because I've had hundreds of chances to have been stuck with one) I would engage with a skilled vendor and interface with the city to make sure the steps to remediation are well understood and the costs quantified before proceeding.

Areas you have market knowledge and access to skilled labor. 

PS get some negotiation skills asapAnd run the numbers on a deal 5 times before buying. 

Some are quite sturdy while others are very soft. 

:I think it's worth mentioning that you can put tile over plywood but it might not hold up as well and I would use polymer-modified thinset instead of regular thinsetI also skip underlayment on laminates that don't have underpad attached because I don't see much added value in the underlayment If you are laying tile over plywood, or any subfloor other than concrete, you want to first make certain your subfloor is stable - no vertical deflection - and then use an uncoupling membrane (ditra, protegga, old-fashioned felt & wire {if you have the skill, but the newer membrane products are better}, etc) to absorb any remaining movement in your subfloor.

Many professional plumbers have the extra skill set necessary to work with natural gas lines, so ask a professional.