Anyone experienced in ecommerce website development help me answer me the following questions please.

1. what is your job scope? (design/programming/hosting/SEO/maintenance)
2. usually how much u charge for an ecommerce website? (local or oversea?)
3. what must be take into account to price a website? (deadline, job scope etc)
4. how long do u usually spend to complete an ecommerce website?
5. one man show or with partner/team?
6. does a contract required?
7. you develop the script yourself or use open source ecommerce solution (ie zen cart, oscommerce)? why?

Thanks in advance! I am urgently need your opinions