Resource types

Hello all,

A little background first...

• We've developed a training interface in Flash8.
• User information such as progress tracking, user notes, etc. are stored in our own database.
• References to our content are also located on our database.
• We're using the Paypal enrolment module to handle course fees.
• We have gone live with Moodle V1.7 but are currently developing/updating an alternative domain with V1.8+
• My field is actionscript, so my php knowledge is limited (but expanding)

We're faced with the following issues:

1. Linking to our interface from Moodle
2. Passing registered user login data to our database
3. Securing our external content from unregsitered users
4. We need to add additional fields to the user profile when registering

The solutions we've come up with so far are serviceable, but far from ideal:

1. The "Link to file or website" Resource seemed the best way to link to our content.  It allowed us to pass user data when launching our interface.
   
   For aesthetic reasons, we'd prefer that our link was an image, rather than a plain text link.  In Moodle V1.7, this was achievable by entering an image tag (<img src="somedomain.com/somefile.jpg" />) into the Resource Name field.  However, in V1.8+, this practice is not allowed.
   
   We could use a Label Resource, but there is no built in parameter selector as there is in the "Link to..." Resource.
   
2. As mentioned, this "Link to..." Resource allows us to pass parameters to the target url.  We're currently passing user data to our database (via php) which allows us to deliver our content, customized for the appropriate user.
   
   In V1.7 the option existed to pass the user's password as a parameter, but this is not the case in V1.8+.
   
3. When it comes to securing our external content, we hit a bit of a wall.  We're okay with passing parameters in the url (with a FORM action), but we would like to include some sort of authentication code with the parameters.
   
   I can see that the list of available parameters includes something called "Miscellaneous - Encrypted code".  I wonder if this could serve our needs.
   
4. Adding additional fields to the user profile and registration forms has proven and is proving quite a challenge.
   
   As far as I could determine, from reading the documentation and forums, there was no easy way to do this in V1.7.
   
   One of the reasons we are developing a V1.8+ deployment is to take advantage of the ability to add custom fields to the user profile.  The problem comes when trying to connect these fields to the registration form.  We can add the necessary fields to the form, but the values are not getting stored.

So, my questions are:

• How can we use an image as our link to external content?
• Using this image link, how can we pass user data and an authentication code to our database?  ...and what is that "Encrypted code" parameter anyway?
• How do we connect our custom user data fields to the New Account form?

Any help would be appreciated.  My brain's going a bit numb from trying to sift through all this php code.

Cheers,
PrplPplEtr