Access Database development for sharepoint usage

Scope:
I am looking to develop a search & answer database from information updated in excel which once tested internally will be used on a global sharepoint. The database will be a search form where the user can identify exact needs and the database needs to return 1 answer or several answers based on the user's search criteria e.g. the user wants to search for a car which has 4 wheels, air con, in blue with a 2litre engine.

At this time I have built, which I hope, is the basic level of the database i.e. the objects and tables however I need some development on the following:
- Link from access to the excel spreadsheet - so once excel is updated the access basic data reflects the changes when opening.
- I also need to understand whether the basic table developed needs to be split into different tables with different relationships.
- VB code between the user search form and the report - the user uses the advanced search criteria and once completed the report comes back with several answers.
- Security lock on updating the basic data also needs to be added - a password needed to update any of the cells.

Any further questions please let m know otherwise look forward to hearing back from you.

Thanks,
Richard