In the major scale the V is the dominant chord, and the IV is the sub-dominant chord. Is it the same exact thing in the minor scale?
"Dominant" in these two terms means fifth. The V chord is called the dominant because its root is a fifth above tonic, and the IV chord is called the subdominant because its root is a fifth below tonic. (It's not called subdominant because it is "below dominant.")
As such, these terms hold true no matter what key or mode you are in. If the root is a fifth above tonic, it is the dominant triad; if the root is a fifth below tonic, it is the subdominant triad. This obtains in minor keys, the dorian mode, etc.
Regarding the frequency of these chords in minor keys, HookTheory seems not to have published that information, because that's not how they went about collecting their data. They discuss it here:
As you have noted, Hooktheory currently stores data in the relative major mode. We chose this because we felt that the majority of progressions in popular music are either in the major mode, or ambiguous enough that analyzing them in the major mode is satisfactory. For songs that are properly in a different mode, the relationships between chords would be preserved (e.g., vi → IV of the ionian mode and i → ♭VI of the aeolian mode are counted as the same trend).
One of the reasons they chose not to focus specifically on minor keys is due to the size of their data set, because over 90% of their tabs are in the Ionian mode.