Perhaps they do it to save energy.

I can already tell from your energy and urgency that you will do great!

If I funnel the cashflow into my mortgage to pay down the principal, I will be reducing how much interest I pay on the mortgage over time (assume the mortgage interest is 4%), but I'm having trouble understanding if this is directly comparable (e.g. 4% mortgage interest vs 2-3% if I invest the money in bonds) since I'm not paying off the whole mortgage in those five years. 

Although I don't want to be actively working on more than one home at a time, I would like to reduce the downtime between completing and listing one house and starting on the next.

When we off shored this job we reduced our cost for this work by 90 percent as we no longer needed someone full time in the office.Key to staying in business... dont pay more for things than you have to.

I'm now focusing the energy to invest OOS, In particular, I like Alabama. 

If the owner pays for water, then there is nothing you can do to reduce that cost. 

A busy office you will get the energy and vibe from other agents that you might or might not get in a virtual EXP type environment.I am an independent broker and have to fight to stay relevant in a hyper competitive market, I have EXP agents call me all the time, I wish I knew if it really is game changing or not.

My thoughts:- There must be a certain cash flow rule of thumb that will allow you to reduce rates if needed to avoid vacancies and continue to cover your mortgage and expenses- Diversifying with other real estate or investment strategies may be advisedOther thoughts?

These cracks are purely cosmetic and don't waste any significant level of energy or pose any security risks.