I think it is about $15 per person - no reservations needed- just wait in line.
The GROUP horse drawn tour (you're in a kind of trolley drawn by two horses) is I think $12. May be $13 now. It's a fairly short tour. You're only moving for 20 or 30 minutes. The same company does give private tours and private group tours. Not sure of the cost.
You don't learn too much about specific houses. For that, you might take a walking tour of the historic district. Plus, several of the most important houses are open for guided tours.
Don't know, sorry.
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