The key is to explain to them that they will make more money by acting as the bank.

If you utilize seller financing, you can sometimes get the seller on board because they get their sales price and you get favorable loan terms2)  They don't need the cash right now (retiree, empty nester) and are financially astute enough to see how collecting interest for 5-10 years on their note can be very profitable.Which argument works completely depends on what the seller needs.   

You'd think anyone who cared enough to have the property mowed would care about that broken window, at least board it up.

That means listing by mid-July if possible.The market is such a hot seller's market right now that the timing won't matter as much as it would in a buyer's market, but it's still a good practice.The key to acquiring properties in this crazy market is to jump on them instantly. 

Lots of money.There are no real short cuts.

As long as you have a plan to pay that HELOC off quickly that is the key. 

He has scholarships and federal unsubsidized loans that cover full tuition, fees and some room and board...but not all.Prob going to need around $20k for college.I have secured a $30k loan using the property for collateral to cover the college expenses.What would you do with the $30k?

Expect them to try to play if your feelings as well, so pack them away and put under lock and key.

What investing methods (buy & hold, turn-key, BRRR, flipping, etc)?

I think I would settle for $100-$150 if it was the right deal cause atleast you are starting your portfolio and building equity as time goes on, but still, availability is key and just not seeing it.