Even with house hacking with a lower down payment (which I am not sure would work if I get a studio size condo), I would still need to pay more out of pocket than what I would pay renting (I can get rent by splitting a studio with a friend for about $1200/month).

You also need about 20-30% down on land loans so keep that in mind!

I think there are two maybe 3 ways to look at this in my mind.  1) you go into it and bring it all up to modern standards but using that old charm to basically take what is there bring it up to modern standards and rent it out essentially I'm thinking cocktail bar or something trendy like that.2) most banks are on really good centrally located real estate if this is true, then I'd consider it for the dirt, plan to scrape the lot and go vertical with whatever the highest and best use is.3) a kind of combo of the two, if the lot is in a good location and its doable, pull the vaults or other "character pieces" out of the building, scrape the lot, and build whatever is best suited for the site there, but incorporate those historical pieces into the final designs.Is the site near a major retail area? 

By keeping these principles in mind, you can optimize your position in the market.

Being flexible in a way that still protects your investment can help build a better relationship.However, if they’re not responsive or don’t show good faith, you might need to take a more formal step, like issuing a notice to pay or quit.

If you are planning to pay the HELOC back after each flip but then draw it right back out to buy the next one, you will have a loan balance most of the time and a refinance might work just as well for you.

This seemed like a good deal to me, since the seller is paying for this and it would also give me time to hopefully refinance into a good rate before hitting the 6.875% mark again.

Do I need to have them sign a new lease with my company name on it not changing any of the terms or do I just inform them on how to pay the rent? 

Keep in mind not a lot of people are willing to do the shorter term rental so everything is negotiable and they will pay a premium. 

They do share their secrets in how you can buy RE using credit lines to pay down your mortgage off in 7 to 10 years.