Mostly correct, yes. The pure BAB classes generally ended up with an extra attack. At level 20, it would be:
- Fighter = +20/+15/+10/+5
- Rogue = +15/+10/+5
Still, tying BAB to speed of attacks seems irrevocably unusual. Anyone in D&D could grab two shortswords, get hasted, and swing incredibly fast. But it was their BAB that determined whether or not they could hit the broad side of a barn.
BAB tied to # of attacks and attack bonus - fine. That's as per PnP rules. But speed? No.
That should be determined solely by the weapon your using (i.e. a conversation of "initiative" and "weapon speed" from the PnP rules).