Can we get bus tickets for going from Bangalore to Goa and back (tickets for comfortable air-conditioned buses) at the last minute (few minutes before the departure of bus) easily, without any difficulty?
The state run transport company, KSRTC has very good well maintained a/c buses to Goa from Bangalore. You can check the availability and book tickets online from their website. Make sure to select service class as 'Premium' to get a/c buses in your search results.
Since Goa being a well known tourist place and April-June is summer vacation, it is advisable to book tickets in advance. Or plan your journey on week days.
You can, but it's not recommended. As mentioned by the previous answer, Goa being a popular destination, the buses are usually booked out. It is preferable to book your tickets at least a day or two in advance.
Redbus is a portal where you can check out the availability of private buses.