I need a commercial developer for some CMSMS modules for proper money

I could also use some reassurance that CMSMS is the way to go with this project.
There are 3 modules (minimum) that I envisage and I will give a brief outline of them. Obviously I want the same person to do all of them. The project is subject to non-disclosure agreements with respect to the content, client etc and I will have to be somewhat vague in the descriptions. Once you have been selected and have signed the NDA obviously you will find out what it is, we just don't want our competitors to get the march on us and we want to make sure we are compliant with all regulations before going live.
First of all, is there a size limit to the Front End Users database? I ask this because the system I am looking at developing could generate as many as 1000 - 2000 new users per week. It's pretty serious - so I need to know what the realistic size capacity for CMSMS and FEU is. I am hosting on a dedicated, managed 1&1 Linux server.
Module 1 - an extension to FEU or possibly some sort of Controller Object.
This is a basic module which extends FEU - it may not even be needed, I don't know. It will store user's basic contact details, personal details, an ID code, hashes of passwords. It could even act as a Controller for FEU with access and control over the other two modules that I would like you to write. So it can see how far a user has got in completing the contents of Modules 2 and 3. It will do address checking against the UK Post Office database for which a license will be obtained by us, in order to verify peoples' addresses. It is very important that we identify people correctly although other checks and balances are in place later in the process, offline, it would be helpful if we at least get validated data.
Module 2 - a workflow to enable a decision on the correct course of action.
A user who signs up to the system (using module 1) runs through Module 2 to find out which course of action is most appropriate for them. There are probably 10 steps in the decision making process and depending on a number of factors, they will get different advice. Some of these decisions are multiple choice (radio button style), some of them are mutliple choice (checkbox style) some of them are numerical. The answers and decisions are stored in the Module 1 object.
Module 3 - an enormous document.
Once Module 2 has completed the user will pay my company a fee to access module 3. In module 3 they enter a vast amount of data from which we create a report which we print and send back to the client. A lot of the information that the user will enter will take time for them to collate, they need to be able to save the partially completed document and come back to it at a later time. They need to be able to see a sort of overview of the whole document to see which bits are missing. It needs to be VERY user-friendly and very hand-holding.
Once they have completed the document, we then perform a number of calculations on the document, including factors and items which will not be available to the user - essentially we are taking the data they have entered and then calculating an alternative scenario for them that may show alternative outcomes given specific inputs. And that's about as specific as you're going to get until we have contracts signed, sorry

The user will also have a free entry text box to provide narrative information. We wish to enable them to select pre-drafted versions of this portion of the document that they can edit if they need to. We also wish to be able to give them a free hand to write what they want, or a way to give a numbered, bulleted, sequential story to explain "what happened" in chronological order, it's up to them.
Once the user has finished an email is fired off to the admin team and though the user can come back and edit if they feel they need to, we move to the next "stage" as it were.
The next stage is where we produce a final, formated document using the data provided by the customer, print it and send it back to them.
Oh and the deadline for first draft is Jan 1st

Simon