Database Design For 'Software On-Demand' Model

Hi there

We are thinking to create a small scale of the "Software On-Demand" model for Support Ticket Management System which means that the client can login to do a support tick and shared the application using the same URL.

Couple options though:
1) We design by table such has a SUPPORTS table with has a foreign key of the ClientID from CLIENTS table. This will cover that client can only can a specific data within the SUPPORTS table.
2) Alternatively, create a dynamic table which is created specifically for "Client B" for instance for SUPPORT table and it will be called such as ClientBSupport table. Something that can be common it will be shared such as like look-up table.

Couple consideration though:
1) Considered client wanting to backup this table. Obviosly it has too querying based on the client id to get the right data.
2) Security withing that table. Is the data needs to be incrypted ... I guess this is expensive excercise.
3) Possibly have a model that access to this table in querying directly etc etc.
4) If the Support table is getting larger and larger and it's not fair for small client accessing the small information which has equal to the one that has big records? Cause it's sharing table.

Any inputs I am really appreciated.

Thanks