Online Bulk SMS Application for Users

I have 1 SMS account through a SMS provider (Route SMS). I would like to use that account (which I purchase sms in bulk) to provide my clients with their own login so they can send sms using my account. 1. I must be able to add a user (User name, password, contact details, email) 2. Allocate credits to that user (in initial setup and when they buy more credits) 3. Show my SMS balance with my provider and warn me if I have sold more than I have credit for. 3 User can log in and sees how many credits he has left (always displayed at top of page), then send SMS until credit runs out. 4. user can specify sending field 5. user can send to 1 or many 6 user can keep address book (complete and groups) 7 User can select certain recipients or groups to send to. 8. Must make sure the user has enough credit to send to all his recipients before sms sending starts. User login section Similar to attached pdf. questions: (1) Will you use ASP / MS SQL DB OR PHP / MYSQL DB (2) Development Time (3) Support / Additions cost after project completed