It depends on your goals, investment criteria, the type of properties, and the Market you are investing in.For instance I am a Buy and Hold investor.  

Depending on your lease agreement, I can see the painting and trim (fill in the trim, then paint it while painting the other stuff) as wear and tear.The garage door, screen door, and floor could all be considered chargeable (again, what does the lease say?)

Depends.

Its a great place for cash flow and depending on your investment strategy there is a very wide range of types of investments.I have been working on the investment side of real estate for several years now and know the city very well when it comes to buy and holds.I own a few myself and have and have wholesaled and worked with a ton of buy and hold investors.You need to be careful of what you are really buy in SA though as what you are experiencing in Austin is happening here as well but mainly on in low-end properties.

The way this is being reference in this post is not in the correct fashion.  

It all depends. 

Depending on your area, renting short-term and long-term can be very profitable as the TDYers have lodging allowances that are based on the average daily rate for a hotel, usually $2800-$4000 per month.

It really depends on you're comfortable with and your goals.

Depending on BTU of the unit.

I'd say it really depends if you are an established agent or a brand new agent.