You probably can get an Indian visa in BKK. The procedure in NY is to drop off in the morning (with $50 fee) and pick up at 4:30 in the afternoon, same day. BKK may be similar. You definitely need an Indian visa in advance.

You can get your Nepal visa at the Kathmandu airport. They want you to have a photograph, but they let me through without one a couple of weeks ago. The fee is $30 in U.S. currency.

Bruce