Developing workflow automation using Sharepoint

I'm designing a workflow automation for a client, which will collect data from an enquiry/order form; add client info to the client database, generate appropriate letters, forms and address labels for items to be sent out.

I'm looking at using MOSS (MS Office Sharepoint Server 2007) as this provides an accessible platform for the client database and document library to be accessed by all staff (as well as by satellite offices via VPN)

For the database I was looking at using SQL since this is more scalable than Access.

Documents are currently in Word format, although these could be auto-generated as required in PDF format for printing, emailing and publishing.

Any code would be produced by Visual Studio, initially from a UML model produced in Visio and then by hand.

Firstly, does anyone have any constructive comments on my choice of technologies or general approach so far? Am I going about this the right way?

Secondly, do I need to build a SQL database for the client database or is there a way of simply storing the data somewhere directly within Sharepoint as I believe this is a SQL database in itself?

Any pointers greatly received!

Thanks.