Stopped paying rent after first month of ownership and had to evict them both at once, which was unplanned and financially difficult.

You might discover that you have a pay a minimum utility bill, like for trash removal, between tenants even if the unit is empty and you're not putting out any trash cans.Other expenses can be unplanned for surprises, like a water heater springing a leak but that's a "normal surprise." 

My goal was to get another property but its very hard for me with unplanned repairs, income taxes, and I sometimes use the savings for personal expenses. 

At least with the 30 yr, you give yourself flexibility and increased margins in case anything goes sideways in the future (loss of job, injury resulting in being out of work, major unplanned expenses with rental homes, medical bills etc). 

Check for termite damage, evidence of rodents, or birds/squirrels nests in the attic.  

At this time, I only have 1 rental property so I want to make sure I keep solid cash reserves in case of unexpected vacancies or large unplanned expenses. 

With all of our struggles aside our third baby which was a bit more unplanned strictly due to the fact that financially we were not really prepared for another. 

@Adam Byrne, It sounds like this was an unsolicited or at least unplanned offer. 

Have a good amount of reserves for unplanned circumstances and invest in whatever makes sense for you.  

Get an old and used squirrel cage fan from a heating contractor.