HELOCs are usually interest only for the first period of years and variable rate and cash refi are like regular mortgages longer term and either fixed or variable...We originally got HELOCs on a few of our properties (which is supposed to be not easy to get on investment properties but our bank did it for us) but I want to lock in the interest rates so we are now getting cash refi's to pull out cash and reinvest in more properties.

If you have both a knob and a deadbolt for the main condo door some people here recommend a regular knob (no key) for the door and have lock only in the deadbolt so they can't lock themselves out. 

My understanding was that each year, you pay taxes at your regular marginal tax rate on: your rental income - IRS allowed expenses - depreciation - interest paid on mortgage.

One question I have, however, is what the difference is between and investor's agent and a regular agent who has expertise in how to buy correctly for investment purposes?

The cashflow listed above is before taking after budgeting $200/month for CAPEX, $113.33/month regular maintenance, and $142.50/month in property management (currently self managing).

You should consider hiring a regular yard service to keep peace with the HOA.

It does give the walls a better appearance but does not look quite the same as regular walls. 

Whatever you can do to increase your savings or increase your income: cut out unnecessary expenses, work a side job, put money into a HYSA as opposed to a regular savings account earning 0.1% interest.

These loan programs are typically used for clients who are self employed & do not show enough income on their tax returns to qualify for a regular mortgage. 

This could mean paying down debt or regular expenses (maybe get rid of a car payment, etc.).