For a rental in a lower income area with a higher crime rate and higher rate of eviction should I estimate higher vacancy, maintenance and/or CAPEX?
I would. It only makes sense. C & D housing is considered that for a reason - rough neighborhood, rough housing, low quality of tenants, etc. - all of which add to your costs.
Yes, generally. Now if you tailor your place to someone who can become a long term tenant, you can end up with lower vacancy as a lower income tenant won't have the same flexibility in moving, but in general turnover will be higher.