When tenants move in, they pick a 4 digit code to use.

Your cash flow is basically rent minus mortgage P&I, property taxes, insurance, income taxes, local fees, utilities (if you pay any), repairs, management, vacancy, evictions and capex items.

Pick a certain niche you may be interested in and go all out!

If I decide to go with model of covering all utilities then rent would be $550-600 a month per student.  

You've definitely got plenty of options to get started utilizing your credit for your initial purchases.

It seems like the general consensus is to utilize a HELOC over a HEL to fund my first deal and then follow the BRRR strategy to keep the HELOC open for future deals. 

If a tenant calls me I do not pick-up and if they leave me a message I will deliberate on the issue and almost certainly respond no.3.

I am still picking up 70 cents on a dollar from MLS. but that's about it.

I would network with other investors in your area and find out if any of them utilize property management.

It is the way I have picked up some properties that are averaging 15-17% CoC with enough equity to pull out now that they are stabilized to buy another one.