My first LLC has all the proper documents filed and recorded internally. 

Keep things simple, do not create any payroll for him and focus on making more money.Now, if he makes $75k net, which is after expenses - then he needs to consider an S-corporation and W2 payroll for himself.Bookkeeping is simple, really: record everything he spends for business in any form that is simple for him: old-fashioned notepad, Excel or Google Sheets if he knows how to use them or apps like Expensify or TaxBot.

Some lenders will do a HELOC in first position (recorded as the only mortgage) I’ve been told.  

It does not make financial sense to bully tenants just becuase you can.

Make sure your financial house is in order, then make a move.  

I know it is possible to individually search county records for each properties' county website which I will absolutely do once I am ready to make an offer, however when I am simply browsing properties online without MLS access, I don't think that should be completely necessary just yet.

@Shasky Charles Welcome and glad you're taking the real estate path to buidling financial freedomSome critical books I'd say are as follows:1. 

For instance, what if the tenants see a big issue that you cannot immediately service and elect to pay rent over to the court causing you to experience financial strain or even default on your debt obligation?

It depends on your financial circumstances.

Whatever you offer is cash in his pocket vs losing it to an inevitable tax lien sale = no cash & eventually no where to live.Most of these 'people' are oblivious to any knowledge of financial security so I'd find out what he would take to just walk away flush with cash.