I've noticed that some charge a flat rate vs taking a percentage of the total rental income.  

We have had a few incidents where we needed plumbers, electricians, etc... for urgent service work - when you cut them a check before they leave the job, they are more likely to come at a moments notice the next time you need them too.We use UDirect IRA Services out of California and have been very happy with them.Dan Dietz

For instance see the article from the Dallas Morning News  (www.dallasnews.com/business/residential-real-estate/20160204-where-home-prices-are-rising-the-fastest-in-d-fw.ece) noting the area on the map that had decreasing prices. 

Some catches that I noticed were:1) Get your real estate license so that you could protect yourself even just to do a wholesale deal.2) Hard money lenders, wholesalers, professionals in law... anyone can screw you from a deal.3) You almost always need a mentor.This makes me wonder, can someone really start from the bottom knowing just a scratch about real estate investing.

As I'm sure you have noticed that BP is full of information and other investors who are happy to help!

Per the lease if it stipulates the landlord has a right to enter the premises with proper notice to perform an inspection of the unit then it's valid.A tenant with a lease cannot keep denying a landlord entry into the property for inspection.

Did the tenant give you 30-days notice that they were vacating? 

You have given them notice, so follow your process.  

I noticed that some houses were next to wooded areas or wooded lots. 

You'll notice if the paint is chipping and that's no big deal to fix.