Module development and code questions

I'm working a site that needs to utilize CCK for some large, content-heavy forms. The problem is the forms are too long for most end-users. I have already installed pageroute.module and have split the forms into various "phases." I've even installed nodefamily.module to group these lesser-forms under one major-form.

I've created a module that attaches specific information to a specific vocabulary's terms. When installed, the module calls drupal_execute to create a vocabulary with all the desired settings, and stores the vocabulary id. Then, form_alter and hook_taxonomy streamline the process to gather information about the term. Life is good.

However, whenever I create or edit products, I can't assign a term from that particular vocabulary. I just get the "An illegal choice has been detected. Contact the site administrator" error. Watchdog reports the term id that I had selected. The database looks fine, and I can even add a row to {term_node} to get the effect I want.

I've downloaded the latest release of Links Package for version 4.7.x and tried to install it.

I can't install it because of this message that appears everytime I visit the modules page:

Fatal error: Call to undefined function: module_exists() in C:\webserver\xampp\htdocs\drupal47\modules\links\links.module on line 15

**What do I need to install Links Package? Should I install or activate other modules first before using Links Package?

Thank You.

In Drupal 5 we have a table_exists() function to find out if a particular table exists. But how can I probe a table being empty? I dont need the actual content, just want to know wether there is data in it or not. At the moment I'm using $empty = !db_num_rows(db_query("SELECT id FROM {mytable}"));to get the total number of rows ('id' is the smallest integer field in 'mytable'). But I bet there is a faster alternative. This query is the slowest on my system (even slower than some multi-join queries). I think thats because 'mytable' is a very large one.

I am trying to run views.module, actions.module, and workflow.module. When I have just views in the modules folder, everything works. When I have actions and workflow in there, without views, everything works fine. However, when I have all three in there, I can't get into the modules screen.

I had a problem with actions.module when I first installed it, where I was unable to get into it's screen, but I stepped back one version on the actions.module, and that part works fine now. However, I cannot seem to find an older version of the views module.

We've been playing with the CAS authentication module, which seems to do everything we want with one exception. When users are not authenticated, they are directed to the CAS authentication page. There is no way to visit the site anonymously. CAS seems to support a gateway function as described in:

http://www.ja-sig.org/products/cas/client/gateway/index.html