What have been your experience with buying SFH in bundles from individuals say 2-3 houses at once?

Then, if you have a lot of equity in those rentals, instead of looking for a HELOC on individual rentals you can get a business line of credit that using the equity in the properties as collateral for the loan.  

This individual moving in is a recent (under) grad looking for a place to live this summer while she is in between schools... she’s going to start grad school this fall.

Dear fellow REIs, I wish you had great Easter weekend.In 2018, my REI goal is fix & flip individual units in multi-family buildings and generate net profit over $100K to learn and test about this industry.

Another way to look at @Michael Le's explanation is by an individual investment.

For example they say you individually were negligent. 

That means I file 1099s to individuals , LLCs, partnerships, sole proprietor etc.- it really isn’t that time consuming or expensive. 

I'm looking for some input for best strategies to either partner individually with each investor and form an LLC to hold the property or, create one or more LLC's with multiple members with all of us working together. 

I don't know what your market is like, but I feel like highest sale price would probably come from selling them individually as single family houses to retail buyers.  

I would encourage you to find a group of like-minded individuals and hang with them.