What is the right Equity sharing for a startup?
If anything, it is low. The key promoter should typically be holding 60-70% prior to external equity infusion. A 40% stake will dilute him down to indifference levels with any kind of funding coming in.
Let me also make a thought clear on this. The key promoter is not one who gets his position for coming up with an idea. He had to be taking maximum risk in the business. In terms of lower salary, efforts put on a daily basis, leading fund raising efforts, ability to do multiple roles and above all promoter responsibilities including being responsible for statutory risks like being legally accountable for things like permissions and liabilities. Ideas are cheap, living them expensive.
Advice aside, here is some hard number feedback for you. The employee pool at 20% is high. The norm is 6-9% typically. Also, 10% is too high or too low for business alliances, depending on what kind of alliances you are talking about. Provide for a 15% investor pool instead for some angels, if you are looking to tap them.
Typically, such complicated equity distributions are done once you have a business which is operational so my advice would be to not burn much additional time on iterating it. Rather think about the business. If it succeeds, 5% is a huge amount to own.