Java Development Tools

Hi Guys and Gals,

Using JDev 11.1.1.6.0 or 11.1.2.0 as needed.

I'm pretty up to date on how to put together ADF programs. I've been through the JDeveloper 11g Handbook, Oracle ADF Enterprise Application Development-Made Simple, Oracle JDeveloper 11gR2 Cookbook set of books so I've got the basics down on how to put together an enterprise level application tailored to well, one enterprise. What I'm interested in now is how to use ADF in a Software as a Service environment (SaaS) to handle the requests of many users.

I've come across a couple of interesting web pages, but nothing concrete on how it's actually implemented:

http://www.slideshare.net/lucasjellema/castle-in-the-clouds-saasenabling-oracle-adf-faces-applications (wish there were sound :( )
http://www.oracle.com/us/technologies/cloud/026989.pdf (Oracle whitepaper "Of course we can do it. We have the whitepaper!)

My question is where the rubber meets the road, how do you actually program it all? Let's take a simple SaaS idea, Forecasting Pro, to expose some of my questions.

Forecast Pro reads sales order history data from a user's database such as SAP, Oracle, Quickbooks, etc. It then stores that information in its own database because reading all that data over the web is a very time-consuming task. From there, the program accepts user modifications, computes the history into a forecast, displays it on the screen, and then saves the resulting forecast into its own database. It seems like a straightforward concept to me for one enterprise, but exposing it to multiple users has got me confounded.

Questions / Obstacles:

1) How to read the data from a third party service? I think most of these ERP systems offer their own WSDL's with which you may submit queries against their database. I've never done it before, but I believe I can setup an entity based on this WSDL to model the data that is retrieved. Does this sound right?
2) Ok, great, I've read in the data with an entity, but then how do I save that data to my own database? The entity I used to download the data is modeled on a WSDL, not my database. For an entity modeled on my database, I simply use a commit operation exposed by the application module. But what do I do now?
3) Multiple "Users" or something else? Does each company that subscribes to my service receive their own User/Schema or would they be configured all under one schema but with table data filtered by user IDs? I would think they would each receive their own schema, because if not, it seems like I'd be pulling an astonishing number of records into the entity middle layer. If they all receive their own schema, how to model with entities?
4) My experience is pretty narrow when it comes to programming. I'm pretty much wholly an ADF guy. If someone subscribes to my service and they need a new schema in the Forecasting Pro database, how is this accomplished without manually running SQL scripts? PL/SQL tied to some kind of registration task flow process?
5) Is there a demo with code out there somewhere? Hahaha - Now THAT would be helpful!!

I know these are pretty in depth questions that might not make a whole lot of sense. That stems from me not really knowing the right kind of questions to ask. ANY insight, direction, playful sarcasm etc. would be appreciated.

Thank you in advance!

Will