Say I do some bus rides in the morning and lot of tube journeys at off
peak time. Is Oyster intelligent enough to handle this?

Peak bus and Z1-3 or less off peak tube would be best capped at the peak
travelcard rate. But peak bus and Z1-4 or more off peak tube would be
cheaper with a combination of bus cap and off-peak travelcard cap. Does
this work or do I need two Oyster cards?

Thanks
Martin