highway bus nagano to shinjuku

I'd like to take the highway bus from nagano station to (shinjuku) tokyo. (from airport to nagano, taking airport taxi) None of the bus companies have an english website. I've translated the bus timetable but I have a few questions:

1) Is it possible to buy the ticket just before boarding at nagano station bus stop? (there are 5 of us, we'r travelling on a weekday)

2) If I have to book, should I book before I arrive in Japan or can I do it when I get to my hotel? (I stay 3 days in Nagano before going tokyo)

3) can i reserve over the phone? (do these companies have english speaking staff)

Hope someone can answer, thank you.

Is it possible to buy the ticket just before boarding at nagano station bus stop?

Yes, unless the bus is booked out. I am not sure how often that happens, but I think it is relatively rare.

If I have to book, should I book before I arrive in Japan or can I do it when I get to my hotel? (I stay 3 days in Nagano before going tokyo)

From outside Japan, you would have to phone. You can try it but I am not sure whether they have English speakers. Once you are in Nagano, you can visit the bus terminal to make reservations. That should be easier than by phone.

can i reserve over the phone? (do these companies have english speaking staff)

Yes, you can reserve by phone, but I am not sure whether they have English speakers.

Phone number of one of the companies along the route (Alpico): 026-229-6200
Phone number of the other company (Keio): 03-5376-2222
(phone will be answered during Japanese daytime only)

The bus ticket counter in Nagano is located on the first floor of the Nagano Eki-mae West Plaza Building in front of Nagano Station (open 5:20 to 19:00).

Thank you uji :) I've found that I could book at the tourist information corner at Haneda. Hopefully it won't be booked out so I'll buy the tickets at Haneda on arrival :)