I.e. you can choose not to spend on a 15 yr old roof today, and probably don't need to, but you will have that roof replacement coming in 5-10 years, assuming you still own the property.

The only issue is that the area that I am searching in doesn't really have any modern buildings which area along the lines that I am interested in, so I am not worried about paying more because I know that there will be a demand for newer buildings.

Once you get an inspection report, this will give you a better idea of what may need to be repaired/replaced in the future.  

Paint, LVP flooring, IKEA cabinets, replacing outdated light fixtures will save you money if you do it yourself and they aren't highly technical. 

Finally, we are replacing 2 exterior doors and an interior door.

I personally have been focused on replacing my W2 job income with CF.

Said the main cause of the issue was a clogged up air filter (I know, my bad for not reminding my tenant about the importance of regularly changing filters (it's written in the lease that he must replace them every 3 months and that I'm not responsible for bills resulting in replacing filters)). 

We also replaced the roof for $7,500.

After getting buckling in just the sunny area, I had to remove the product and replace with something higher quality. 

Cash flow is definitely important (and I don’t know your finances) if you need to replace something major like a roof and you’re never making that money back.