I’m pretty sure you can

I was in a group of 30 people in a tour group but the tour company booked it. The boats were full and it was busy

5-15 minutes only

In Thekkady, you’ll find two days too little. But, you can go for Periyar Lake, Tiger Reserve, Spice Garden Tour, Kathakali Show, Kalaripattu Show, Safari for Elephant sighting, and the local food which is a very vast selection. There are State Tourism guide kiosks to help you make a better selection.

better to be on the safe side and postpone

Actually you have to go with your ticket to the BUS stand and then they will drive you to the forest in their own buses. Where you have to buy the tickets for the Boating

it coasted around 270/- per head,its better to book early though online booking.

I would definitely not recommend to book online as there have been issues in the past. It is easy to get tickets on arrival even during peak time. I would recommend to reach early and try for the morning slot around 8:00-9:00. Best time for sightings. We had been during Diwali to this place and had no problem's with the booking. Just remember that the place is full of Monkey's, so make sure not to keep any eatables outside or in your hands.

It's a boat number.