For your existing vacancies - there are no proactive measures - simply active or passive measures you can take.

I then did some wholesaling, land flipping, did some more buying and am now just doing lending to build up active income.

SOLD comps vs ACTIVE is very important.

I'm actively seeking mentorship from someone with experience in similar markets who can shed more light on this process.

I do try and tweak pricing just so it sees that there is active updates on the listing sites.

All the information is there if you actively pursue it.I think that many of these coaching programs are designed for those who want someone to walk them through the process.

He’d likely play the role of buyer’s agent, contractor, and rental listing agent—something we successfully did last June.

I think the first question is do you want to be an active investor or a passive investor? 

Quote from @Gregory Wilson: A few things there, Brendan.First, an LLC with you as a member and your (wife, son, pal, etc.) partner as a 1% member will file a Form 1065 which is about one tenth as likely to be audited by the IRS as a Form 1040 with a Schedule E rental activity (which I presume you will attempt to show is an active business).Second, you want an LLC because when your local Alabama handyman drives his girlfriend's uninsured truck into a van load of U of A medical school interns on I-22 when he goes  to get some shingles for your roof, on your business, you don't lose everything you have or ever will have to an uninsured claim. 

Deposits will not be returned (full or partial) until all tenants move out.If Tenant A didn’t come to you to get part of the deposit back they may have gone to tenant B, but they most likely walked away from it and I feel it is between tenant A and B to sort it out.Personally I would return it to tenant B, the active tenant in the current active contract.