Clearly my expenses for the wooden siding maintenance will be higher than brick as will need to repaint and touch up every 5 years or less, and the service for the window units will likely be less (especially since my lease states the tenants are responsible for them along with appliance repairs under $150 for that rental) along with them being cheap to replace and fairly serviceable.You have to look at each component of a given property and estimate the maintenance for it based on what you know, what you have seen as best practice here, ways you can minimize or avoid the expense, and based on quotes that you get from contractors as part of your diligence period.  

They seem to be very conservative and focus on avoiding getting beat too bad by the market vs. helping your get wealthy.

Is it worth being trained by a brokerage or is that a situation I should avoid at all costs?

This is exactly the reason why you should avoid workmen's comp.  

I'm not looking for an excuse to avoid giving the tenant their money back.  

If a tenant of mine has been bad, I try to avoid 'trashing him/her' to a prospective landlord by simply pausing after being asked a question.  

and...2) What are some words of advice for screening different people in the real estate world - put another way, what are some types/people to be wary of or avoid altogether?

Avoid big banks and credit unions.

All properties require maintenance, you'll never get away from that, but BIG expenses are (mostly) avoidable in the near future if you buy right.

We have been looking on realtor.com so far, trying to avoid a realtor for the added costs.