Manufactured home HVAC contractor issues

[Val Dufour]

Hello all,
I'm a new investor and I'm running into my first large problem and just wanted to poll an experienced group for some insight.
My Situation:
I live in Colorado and have family in Mississippi. By a random chain of events, I found a good deal in Mississippi on a manufactured home that needed work. It was a reo and the appraisal came in at substantially higher than the purchase price so I bought it, cash. I was able to see it in person for the purchase but am now remotely having it rehabbed with a local "friend of a friend" type contractor. Originally it sounded like a great deal, but we all know how those stories end up. It's been a bit of a night mare since it started. It's my first rehab so take that in mind. I have no knowledge base of what right looks like.
I agreed to pay him upfront for expected material costs as long as he provided a receipt for the funds.
The first problem is that he started working on the roof, then didn't properly protect the area needing work before a storm so now there's water damage that he's responsible for. Now he's out of town for a week(which I was expecting) but my family who is there and is involved are seeing things that don't add up in their opinion. They have no real estate experience and are just going off of general perception.
The next big problem is that he is supposedly ordering a new HVAC with the A Coil and outside unit that he wants to install himself. Does he need to be certified to do that? or is it legal for him to do it as long as he's capable?
The bottom line is that I don't know what to do. I'm remote and I"m getting stories from all directions and I don't have the experience or the presence to get to the bottom of it.
I would really appreciate input on what my options are. There are two main things I'd like addressed.
1) The AC unit and install. I realize you would want someone experienced to do it, but is there a certification required? and if he's already ordered the AC unit with funds I provided, do I legally have the option to reverse that and have him return it?
2) If you enter a contract with a contractor and then realize you made a mistake, what are your options? To be perfectly honest, I'm not sure how bad it is because like I said, I'm not there, but my family who is involved seems to think it's not going well. It's very stressful not being able to see everything first hand and this is definitely a large learning process for me.
Anything else you see that might be worth addressing also.
Thanks.