Understand the fees involved and calculate the total cost for an entire year of management so you can compare the different managers.

Should I make an offer with the qualification that all furnishings, dishes, pots, and pans stay, except for "personal" effects?

Most cost segregation firms will provide a free cost/benefit analysis quote to help you determine if the tax benefits from the study will outweigh the costs.

Your referencing effective age vs chronological age. 

If I were to purchase an Airstream to use as lodging while I travel across the US to my rental properties, make repairs, and perform lease turnovers, would I be able to not only deduct fuel and campground costs but also depreciate the purchase price across 5 years? 

I made a few thousand less than expected but I figure that's just the cost of doing business sometimes.Based on my experience I wouldn't let the remote possibility that a homeowner might go into greed mode dissuade you from doing these deals.

Quote from @Anthony Sigala: We are all aware of the 1% rule--the gross rent produced by a property must equal 1% of the of the property's acquisition cost.

You also will still need to manage your property manager  - ie, stay on top of expenses, ensuring your property is being managed effectively etc. 

It cost about $100K, but it would have cost around $200K if she were to do it from scratch.

You pay your agent at closing (think of it as an additional closing cost) Depending of the situation and of these options can be used by you and your agent to negotiate with the seller.