Assuming you would buy the foreclosures from the county auction, foreclosures are typically harder to finance.    

Typical breakout is usually 60/40 but depends on the property.

Depending on size of lot and # of structures and impervious surface these typically are not cheap

How long is the typical due diligence on a property like this?

Typically it breaks in hottest or coldest day of the year and that’s when you will pay a premium price to get it replace or fixed.Personally I would not want to install a refurbished HVAC system, I think you’re better off w new installation and not have to worry about it for a long time.Typically when I purchase a unit and I know HVAC system is over 15 yo I know that sooner rather than later I will have to replace it and I plan for it..

"Site control" (sourcing a new deal under contract) is typically one leg of the stool--the others are capital and experience (such as rehab & project management, etc.). 

I currently work as an engineer and plan on using income from my day job to finance downpayments for rental investments.I am interested in out of state investing as the cost to enter my local market (SF Bay Area) is a lot higher than I can afford and don't typically provide cash flow.

Typically, you are supposed to do a final walkthrough the day of or day before closing to avoid issues like the garbage issue you explained.

What is more typical is you being the guarantor on the loan and title being held in LLC name.

So in that sense you've got plenty of time - both to set up the 1031 and to continue your due diligence for your replacement properties.And although it may feel daunting you've done a fantastic job of distilling down the questions.