Module development and code questions

I'd like to authenticate users against our typekey server. From what I understand, not very much have to be changed, but how do I make the changes in a way that makes it as easy as possible to upgrade Drupal? I have read the module development documentation, but it only explains how to make new modules.

hello everyone... I'm very new to drupal... and loving it. :)
I just learned about the CCK module and have installed it.
What I'm wondering is if I can enter any php code into a custom text field to dynamically pull in data from the database.
For example, could I use CCK somehow to create a form users fill out to post a review of products (this is hypothetical) and the product listing drop-down-menu is one of the custom fields via cck... but the options are populated by pulling in that data from the database of products i have on that site?

I would like to replace the Drupal searh box with a form that posts to our intranet search server, not the drupal server. To do that, I was thinking of rewriting search.module. My question is, do I need to keep the module name, search.module, and/or the function names inside the module as they are now?
I.e. if I give it a new name, say mysearch.module, then I would have to change the name of some function such as search_help() accordingly to follow the function naming convension. If I do that,

I need to display a nav block based on category OR a node id. I've got the category part working, but when I view the content for this node (http://www.example.com/?q=node/1), the block is not displayed. Any ideas on what I'm missing?

I am working on displaying a custom menu block based on all of the pages belonging to an assigned category. The problem is that the block is showing up on every page, not just the pages in the category. I've selected the correct option and put in the code below - "Show if the following PHP code returns TRUE (PHP-mode, experts only)".

Since I only need 1 category specified, I'm using this code with the category specified as "my_category". Then in my list of categories, I have a category named "my_category". (no quotes)

I've written a BBCode filter for drupal and while I'm waiting to get CVS access I thought I'd do a quick post here so that people can test my parser if they want.