How material does their involvement have to be?

Everyone wants the easy, simple answer to how they get Foreclosed properties, but the truth is, it takes time, energy, research, networking, studying, money for advertising/gas/marketing materials, etc., and most importantly, persistence! 

I have been reading a ton of material (including Bigger Pockets books!)

Do you want to just shadow some active investor/developer to learn what they do (help them with spreadsheets, or pricing materials/labor, or maybe befriend a real estate agent to help them as a volunteer.  

The place we stayed at right after had the full bulk costco packages. 

This is refundable to them provided that their pets do not provide cause any damage to my home.2) I only allow one pet and I require them to upload a photo of their pet at the time of their rental application to protect against any changes.3) This one isn't necessarily a guideline, but a practice I implemented: I have tenant-proof AND pet-proof materials in my rental such as luxury vinyl flooring, quality tile, and furnishings that can withstand pet accidents.I am also considering charging pet rent, but it is a mere thought at this point.

(technically, they have up until the 15th day of the 4th month of when they last furnished materials or labor)   So, you do not want to buy a bunch of liens. 

Inflation is 2 to 3% on average.in 2019 about 73 million boomers & about 73 million millennials. some millennials seem happy as long as they have an internet connection & don't seem too interested in material things like sfh. 

Which leads me to my question: Is there a specific resource or set of resources (material or person/mentor) that I can learn from on how to find, analyze, and purchase multi family deals?

Not sure if any materials have gone up in prices since you lined yours.