I am evaluating 6-10 unit apartment buildings and wondered how others have structured seller finance deals?   

NOT my first rodeo on this subject and I wouldn't suggest a verbal anything.You don't talk to them you manage the issue by giving them a infraction notice..

@Michelle Martin sorry to hear about all this:(As mentioned already, create notes - we suggest using Excel to build a timeline with: 1st column date2nd column summary of what happened3rd column copies of supporting emails, pics, etc.You can color-code the rows for even easier tracking.What has previous PMC stated about their mistakes & "fraud" repairs?

I'm just wondering if there is a way to optimize the amount of cash I pull out of the existing and the amount I put down into each new property to get the maximum cash flow and build equity. 

I’m constantly worrying, I was wondering if there is anyone I can talk to about the situation that’s gone through the something similar? 

I would suggest speaking to local banks and credit unions.

I'm actually wondering the same question for exterior changes - how/when to know if siding should be changed or new front porch built: is that a designer as well or architect?

Thanks for your comments @Greg Dickerson, I'll start to investigate about the things you suggest! 

What do you suggest I buy and which area?

Any thoughts/tips/suggestions/warnings/advice is welcomed!