Are you replacing the whole system: condenser and compressor? 

That's a gross return of 45% ....which disappeared after I had to replace the AC condenser for $2,500 the second year I owned it.

Also, I want everything in writing for peace of mind, so if they have questions they can always send a condensed email back and we can address them one by one and I can show proof that their concerns were addressed in a timely manner and set expectations.

I’m assuming you mean just the part that sits outside the house (the condenser unit)?

It's not perfect because images can be outdated, but it allows me to cover way more ground in a condensed period of time. 

Some of them drain it down into a pan under the fridge and the condenser fan evaporates it.

Instead of planning out for a 12-month year and evaluating every quarter how you're doing and setting goals for the entire year, you condense the year down to 12 weeks and set goals for the 12 weeks, and reevaluate every week how you're doing.

I have heard that the furnaces can cause ice damming on the roof and the condensate line could freeze. 

It may be setup so a slip causes them to crush your coolant lines or your condensate drain. 

If you stretch yourself so much that you have literally nothing in reserve, you are setting yourself up for failure.What I would do if I were you is start scrimping, saving and condensing your expenses down.