Lean Doughs

Does anyone have an idea whether there is a general rule of thumb for the amount of yeast required in any given bread dough recipe?  I understand the Baker's Percentage but since it excludes yeast from the calculation, I would think there would be a way of figuring how much yeast would be required for any given volume of flour. No?   My store does not carry instant yeast and it appears the only yeast I can get around here is rapid rise or active.  Not sure what the difference is but I was under the impression rapid rise was for bread machines.  Any help would be appreciated.