There done, this is an extinction level event for discount/flat-fee brokers because there discounted system was reliant on an ocean of ready buyers/buyer agents bringing buyers because that's literally how they could be discount, they just listed on MLS, did the bare minimum. 

Specifically, I'm interested in understanding the discount buyers are typically looking for.

This depends on the local MLS so I can only speak for mine but the way it works here is you get a discount on MLS dues if you are a Realtor/ NAR member.

My focus is on finding a discounted SFH or Townhome that can act as a live-in flip for 1 - 2 years to maximize rent potential before it actually becoming a rental for my portfolio.

Members often share investment opportunities, like off-market properties or discounted services from contractors so I'm quite sure you would find it beneficial to your journey.

Maybe you could find out if that house is also for sale @ a discount and now you have 2 properties that you can improve and drive the equity up.

I think right now with rates where they are, there is a smaller buyer pool, which gives opportunity to get even greater discounts. 

Try this device to measure the noise: https://www.amazon.com/Indicator-30-130dBA-Detector-Temperat...You can also stick the same device by windows and doors to see if temperature drop - which would indicate an insulation issue.In addition to getting an Energy Audit, you may also want to look into any state, local or utility programs that offer discounted or financed energy improvement programs.

I have already gotten my living trust out of the way a while ago, so Seth said he would discount my contract.  

Another valuable skill to learn is how to find off-market or deeply discounted properties.