Rent will increase and addition $50 after that.

Plan - close in September, renovate the empty and ask for an additional $70 from that one, an additional $50 from the one downsizing and remain the same on an efficiency. 

We needed additional income as we were purchasing our home, so I got a job at a financial firm (had to inactivate my license) and have been there ever since.

depending on your lease, the original tenant may be harboring the other tenant and be violating, I may consider discussing with the tenant (assuming the lease specifies who can live there for how long) that they are in violation of the lease, and you can remidy 2 ways, volunatilly terminate the lease and resign a new one with the additional tenant, or you can go down the eviction route. 

In addition to spreadsheets, I was curious if anyone uses a checklist when analyzing properties; a series of questions, reminders, and information to acquire as a guide you use? 

They are definitely hands off, 1031 exchange eligible, and have been a wonderful planning tool for a lot of folks...including those that still own/manage real estate in addition to their DSTs.  

From my previous learnings, my initial strategy is to invest in a duplex and "house hack" while gaining more experience to invest in additional properties. 

Additionally, my parents are giving me the option to receive a lump sum payment to go toward possible rental property purchases.

The only benefit to a lease option, really, is that you can charge them rent plus additional for the principal balance, force them to pay the taxes, and take care of the property.

I wouldn't put a lot of weight behind that "guarantee."