For example, I have a client who lives in Franklin, TN and purchased a second home downtown Nashville, TN with the intention of using it when conducting business downtown, entertaining clients, etc...  

Depending on the area.

Look for areas with high need for rentals, growing numbers of people, and rising business activity.

Typically closing costs are around 1.5-3% of the purchase price depending on buy down points, tax proration, etc.

I would set up an entity that buys the property, you'll put the capital into the business and find an equity split that works for you.

Even if you create a non-CA LLC, if you are managing the business from California, you will likely be deemed to be "doing business" in California and therefore likely subject to CA taxes.

I value the role of having a solid network, which I've established in the Kansas City architecture realm, and am excited about getting to know you all in the real estate business in the KC Metro area! 

Also, most decent STR property managers will be happy to offer projections for properties, or even realtors who do a lot of STR business as well. 

It depends on your county.

I recently found an agent who is willing to list properties at a discounted commission for investors in return for repeat business.