We’re both in college, and while we both have respectable jobs (by college standards) and strong credit, we’re aware that it’ll be very difficult to find hard money loans in our position.

They will look at your credit score, experience and liquidity.

Once you pay down mortgage, you can't get it back out until you sell the house (or pull out a line of credit).

Or you could just get a personal line of credit. 

Otherwise I usually just track down the previous owners and get them to sign Quit Claim Deeds to me.

You can also have the funding and then not get the property under contract and then you have to reapply for the loan, ping your credit....not the best way.Both options work, it depends on you as an investor and what you feel comfortable doing.  

Could be debt ratio, down payment, credit score etc...Try Home Possible. 

These are units that are occupied by people who have low credit, hard to prove income, rental history issues, crime issues, etc. 

They are all slightly different on things like, can cash out be used as cash reserves, seasoning, LTV's and min. credit scores.

I only own 3 properties, if you own more (or have mortgages on more than 3), cant remember, they will not do equity lines of credit for investment properties.