I don't think the bottom edge distance will have any noticeable impact on the tension and shear capacities of anchors. Even under compression, it will not be a problem as compression is largely resisted by bearing stresses generated by the baseplate contact with the concrete surface.
Yes, there will be some contribution from continuous footing to resist sliding. But, determining the exact amount is difficult. I have designed many isolated spread footings for PEMB structures, but, never considered any contribution from continuous footing.
