Yes, B25003 is a good table to use, since it's only occupied housing units as the universe. Homeownership rates generally do not include vacant housing units in either the numerator or denominator. To calculate it:
owner-occupied housing units / total occupied housing units * 100
if using table B25003, it would be B25003_002E / B25003_001E * 100
Also, if you want it for each U.S. county, you will be interested in the 5-year estimates rather than the 1-year estimates, since the 1-year only has estimates for large counties.