Keep-in-touch - internet data base

Hi, Keep in touch is an outsourcing - customer contact Management Company. As part of the company's establishment I would like to build back- office website which will be capable of handling all the data base management to multiple companies. (Including interface and secure accesses) e.g. every member (company) would have the ability to get into his own clients, manage them, export the file to excel , however the main control of the data base will be held in "keep in touch" hand and it will be able to allocate different access approvals to its users (add, edit, delete, export, import etc.) Basically the data base will be built from 3-5 tables – however I would like to have the ability to add other tables (should be provided after receiving the price offer) and will have to support In addition the database will be able to support about 5- 8 screening options. After choosing the Freelancer I will be able to supply with a full Microsoft Access data base – so the main issue is to convert it to web tool and the security issues. It's pretty new for me so if you have any questions I would be more than happy to answered Best, Yossi