As for the percentage of supply, I can't say because it's an unlimited supply and we haven't made any premine for everyone to start from the same level.
You could also offer a number of coins instead of a %.
Could it be you have no clue and want the developer to suggest terms? Then continue ignoring everything I said, and hopefully you'll attract talented developers and not scammers.
Yes I am ready to give a large amount of $ZERC to the person who will work for us of course. This will be negotiations with the stakeholders.