Before today I actually thought I was a pretty good landlord...provide a quality product...have all my tenants setup on routine maintenance visits, and even send out gift cards around the holidays. 

Selling a single family home that is well located in a nice neighborhood in OC in order to buy non-performing notes is trading down in quality and up in risk ...

We want to leverage networks and service the retiring boomers and emerging millennials demographic (smartphone-driven) Uber/AirBnB savvy tenants.   

However, I noticed the quality of lead initially isn't great.

Speed, quality, price. 

These are usually a little harder to find good quality tenants for. 3 bedrooms generally means a family with school age kids so really April/May/June are the prime rentable months for these. 

For air conditioning in this scenario, you could install a ductless heat pump if there is sufficient demand.Regardless of your choice for heating system, you will get your best bang for your energy efficiency buck by improving the building envelope (air sealing, additional insulation), which may necessitate the addition of a ERV/HRV to maintain air quality in a tighter building ... but it may also allow you to use a smaller boiler/furnace to condition the building.

If you want carpet, go with a super cheap frieze and get a good quality pad with a moisture barrier (8lb pad).

My comment had the caveat of being a nice neighborhood that would attract AirBNB quality clientele.

Otherwise, a rehabber is taking a significant risk by doing a rental-quality rehab -- if he can't sell to a landlord, he'll typically need to re-renovate to a higher level to get it sold retail.