There's a checklist from that embassy that you need to follow, if I remember correctly.
However, for a single entry Non-B, I highly doubt you need proof of onward travel and accommodations; the government will assume you'll get an extension of stay.
Edit: Non-B for business purpose checklist:
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Non-B for employment:
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Non-B for being a teacher
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Choose the right one, fill out the box, and send the packget together.