I am not in HVAC.
You are joking correct? So you come into an HVAC forum where HO's are talking to professionals that make their living in HVAC. The rules are no DYI.
The not so funny thing is these men and women went to school, somce the school of hard knocks, have taken tests and are certified to do the work. Including the EPA tests for freon. Which makes me feel good they are following the law. This is how they make their living. And I am yet to see one post where they are soliciting business unless someone asks for a referral.
Would you email a Doctor and ask for directions on how to remove your tonsils? The tools are all available even on Ebay. You could always go for a check up when finished.
I have owned rental property and you can deduct the install just like stated. It sounds to me like you are cheap not frugal but cheap.
I recently had two heat pumps installed by a licensed contractor. My brother in law who totes and fetches for an HVAC guy said come on we can do this ourselves. Buy the equipment for wholesale off the internet...find someone to startup up...save money. Excuse me but NO WAY.
I did have a couple of issues after install. Guess what? A friendly call to the installer and he was here and made everything right. I also sleep good and comfortable at night knowing me and my family don't have to "sweat" because I wanted to be cheap. Also, I have a solid warranty.
Also, please don't wash that oil into the land. The USA and world is becoming a cesspool and we all have to live on the planet that we have.
So my advice is to hire someone. Do your homework, get references but hire someone. In the long run you will have less headaches and a warranty.