Contact a Property Manager in the area to ask about vacancy rates. While you have them on the phone, ask their opinion of the property. They’ll be able to give you a sense of the types of tenants you’ll be seeing.
Capex really depends on a lot of factors, such as when the property was built, and when major items (roof, HVAC, etc) were installed or last overhauled. I wouldn’t buy a property without knowing those things. If the roof and HVAC are on it’s last legs, 15% for capex probably won’t save that deal.
Repairs are also often dependent on the year the home was built. The older the house, the more repairs likely needed. They also depend on the class of tenant you have. Higher class tenants tend to take better care of their property and often handle many repairs on their own. Again, the PM should help confirm all of this for you.
It’s also hard to assign a % for repairs and capex without knowing the value of the property. As a percentage, repairs and capex for a $500k property will be much less than for a $200k property. E.g., replacing a toilet should cost roughly the same in each of those properties. As a result, the repairs as a percentage would be much less for the more expensive property. What’s the property worth?