Finally, how much above the down payment should I have in reserves for any unforeseen capital expenditures?

In addition lenders, both community banks and Fanny/Freddie, will require you to have 9-12month of mortgage reserves in cash.

You should have enough money to purchase, renovate/repair, and still have a reserve for emergencies. 

As newbie investors, my partner and I are really taking this time to build cash reserves, increase credit scores, and take in as much information as we can.

The more experience and support they have the better.The vetting of their financial history and reserves are the same as any other lease.  

If you do them one after the other, I would expect the second lender to not qualify you unless you have plenty of money for reserves for both properties.

Continue building cash reserves to help acquire next property via owner occupied financing.

(We are actually expecting an unsolicited offer today to buy ours).This is coming from someone that has been super host since we launched (or as soon as we were first eligible), offered but declined Plus, low acquisition and rehab costs, and maintain 9 months of capital reserves. 

You might be omitting (Repairs and Maintenance & Replacement Reserve CapEx) and also missing closing costs on the purchase and loan.

To make things even sweeter, she also agreed to wrap a sizable "loan" of $50k for future repairs and reserves (or other projects) into the purchase of the property, financed at the same interest rate for 30 years, brining the total loan amount to $155,500.