I think any pitfalls I would have experienced with real estate after several years has been condensed into the last 9 months. 

You'll have a new AC condenser on the outside and one or more inside units.

When that permission is requested, we advise them to use a professional to install, and that they will be responsible for any damage caused by the AC due to improper installation, including creating a hazard either by protruding into a walkway, or condensate draining on a walkway creating a slipping hazard; or draining improperly, damaging interior or exterior walls or siding.

My first spreadsheet is condensed information form my mortgage broker and lists on the Y axis (vertical): mortgage terms, rate, APR, fixed term, years, credit score, loan amount, sales price, percent down, down payment, FHAfunding fee, Total Loan Amount, Estimated Monthly Payment, Principle & Interest, Homeowners Insurance (Flood + Home), Property Taxes (1.23% home price in my county), Mortgage Insurance, HOA Dues, origination fee, appraisal fee, tax service, flood certification, credit report, attorney's fee, title insurance-lenders, title insurance-owners, recording fee, verification of employment, survey, home inspection, water/septic if well, pest, 1st year homeowner's insurance premium, homeowner's insurance escrow, property tax escrow, per diem interest, down payment, closing costs, prepaid expensesOn the X axis (horizontal) I have the numbers for 200k, 250k, 300k, 350k, 400k broken down into whether it's single family or multifamily, then FHA or conventional2.)

Renovated Kitchen, 2 bathrooms & installed new furnace & condenser.

so many reasons it is hard to condense it into a post.  

Also, if you decide to bin the old hvac system, have them move the R22 into the outside condenser, and then put that into storage. 

Installing a traditional a/c would either be an air handler or a furnace with the ac coil on top and an outside condenser both options would need duct work.  

We have installed quite a few & believe it or not the Goodman furnaces & a/c condensers have been the least problematic.

It took them almost 2 months to replace the condenser.