Are you hiring a GC or planning to GC on your own? 

These can be fairly automated for you as well to help save you 10% which on 2 units could be well worth it. 

Their argument, if I understand it correctly, is that I have two buildings on the property.

I've been mulling over something and wanted to get your take on it.

If you are renovating your rentals you need to let the current insurance company know what is going on, if they send an inspector out there within the time you could get kicked from the policy too, and not easy to get back on one.

Quote from @April Birdsong: I will be closing on my 1st STR/MTR this month. 

These are the keywords that stand out to me in your question:sources, websites, best deals, systems, step by step, factors.You are focused on all of the wrong things.

Congrats on your experience and welcome to the forums! 

If you’re on a tighter budget, corrugated steel is a good compromise, offering a solid roof at a more affordable price, but just be aware that it might require a bit more upkeep down the line.Best of luck with the roofing decision.

I am putting it up on Facebook, Craigslist, etc. but is there anything else a newbie can utilize that you have found success with?