They are young, still in college one more year with minimal income.  

A few things I do personally for clients is: create a P&L, market to my buyers list, pre-market the property online where the target audience is, and make a plan for bookings and the booking calendar to minimize losses while up for sale and operating simultaneously.  

It's a slow and steady journey of sacrifice, living below your means, delayed gratification, and just getting the snowball rolling down the hill.

They are young, still in college one more year with minimal income.

She found out they were trying to cut her out of the deal, the owner will delay things till the agency agreement expires.

Is it really that big of a deal if I have to delay it it and sell in July or August?

I'm not sure what you meant about the PM's explanation about the tenant moving out of their last place but if they were delayed moving into your unit, I don't see that as your problem and they should've still been paying rent, or your PM should've been continuing to market it.

Working with a HML requiring a non-refundable earnest money deposit…What due diligence do you perform before sending that deposit to minimize risk?

Not bad but need to be sure its worth it to rent out to people, get and pay for LLC for liability purposes, and minimize your personal use stay at the shore for 14 days? 

I'm trying to minimize headaches and risks as much as possible.