@Victor YangWhy are you not reaching out to a NC real estate attorney to draw up a document that spells out the agreement that you are looking to do with the tenant?

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Be transparent and document everything.3.

Letters to investors are not governing documents—whether you are required to fulfill this capital call depends on the language in the operating agreement, so I’d start there.

This is a straightforward and common approach.However, make sure to document the change in the lease renewal or addendum, specifying the new security deposit amount.

And the obvious, again well documented, FOR PROFIT.... 

Would you have any recommendations, in your experience, for what to look out for in the documents that would be red flags or items that would negotiable?

Also the agreement was more beneficial to them than to me. 

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

There's only about 2 types of work permit I know: closed  vs opened work permit: where the former has a condition of which employer the holder of the permit can work for (it's specified on the document); while the latter does not have that condition; hence, the holder of the open work permit can lawfully work for any employer.