Unfortunately I threw away the brochure...:rolleyes:
I did the one-day trip just recently and liked it a lot. For me, there was enough time at all the places we visited. According to our very knowledgeable and funny guide you should consider booking ahead, as in season they make the tour also only as a bus tour. The space in the train is limited - if you come too late then you will only get seats in the bus.
The one day tour costs 875 Rs including all entries, breakfast, a meal and snacks and chai. I do not know about the costs of a car. Of course this would give you the freedom of stopping on the way, but you would miss the train ride. Which is nice (lots of tunnels, nice views).
There was one couple that was on the two day tour. They came with us till Araku railway station and were then brought to their hotel. We met them after our sightseeing in Araku at the hotel again where we were having our meal - they in turn just finished their meal.
After lunch we all attended the Dhimsa Dance and went then on to the Borra Caves (without the two day couple). So I think that on Day two you would join the group after lunch and therefore go the Caves on day 3 of your initeary.
Surely, the good thing about the two day tour is, that you can spend the day in Araku itself. The one day trip is a loooong day.