It really depends on what this business/sales guy will be doing. If they are just going to be like a contract sales person, who has other accounts besides yours, then the equity would be on the 1-5% range, depending on the time they put in and the sales they generate.
If this person is really going to be part of the team and work full-time to get deals and craft the direction of the company, then 10 to 15 or even higher is warranted.
Regarding the perfect candidate, I would look for these traits:
- Knowledge of your market space, including knowing a lot of customers
- Track record of selling or developing business in a startup, where they were used to thin budgets
- You get along with them at a personal level. This one is critical. Do not hire anyone you don't get along with even if they are a super star. It will just create friction.
- Shares your vision for where the company needs to go.