Paradox, yes you can get the visa at the airport but it saves a lot of time if you go to https://nepaliport.immigration.gov.np/ , then visa prior to approval - entry point TIA, enter your info and get a qr code. Then you can go straight to the banking counter, pay and proceed to immigration.

Ehho2, thanks for sharing your experience with the hotline. I was being half facetious with my earlier comments as I had not received responses to my emails to NRNA, but it seems like you had a good phone call with one of their contacts.