Request for advice

Dear From Builder developers and users,

I'm about to start working on a module where I believe Form Builder can be a valuable contribution.
I'm a bit lost though trying to figure out if the module can provide the functionality I'm looking for by
going though the source.
So, before spending allot of time on something that might not work after all I would like to ask you for
some advice on the use of Form Builder.

This is what I'm looking for:
The module allows selected users to define "services". The webform in which the service is defined is
composed out of a fixed and a variable set of form fields.
After the user has filled out the form and optionally defined a number of new form fields, the form is
processed. Processing involves extracting data to store in the DB and extracting full form fields to use
in other forms exposed elsewhere.
It is the combination between the form building and the flexible processing of FAPI arrays afterwards
why I believe Form Builder might be a good tool. Questions I have are;

- How do I go about using the Form Builder hooks to load the form for a service form the DB and expose
it for editing and retrieve it for processing once the user is done editing?
- Which hook can I use to load the FAPI array for a particular form from the DB via the Form Builder API
and optional return a modified one for storage again? (related to first question)
- Can I store the FAPI arrays in my modules DB tables instead of the Form Builder cache?
- Is it possible to label the fixed form field so they cannot be changed by the user?

I would appreciate some advice/pointers.

Thanks in advance,

Marc