Generally technology (intellectual property) shares in 5 - 40%, depending on the technology of the high and new degree. Catering cooking technology, generally can not be recognized technology (intellectual property) shares, unless there are special secret skills, can be considered, but not a lot of. For C suggest you consider within 5 - 10%. You are to incentivize him to get the business, you can also use the salary plus 5% equity dividends.

For B, you can negotiate with him, you 50%, he 45%. Equity, you can you first give him advances, from the dividends gradually back to you, and finally do solid his shares. This is better.