Module development and code questions

How can we redirect to a specific page in drupal. I have found posts related to redirection only after submitting a node form.What I want is to be able to redirect to any page from anywhere.For eg. If I am in a certain function like modulename_function then I want to be able to redirect to any other page from there .

I'm working on a site that uses Ubercart and sells a highly customized product. For shipping address reasons, only one item can be purchased at a time through the cart. What I would like to do is, if there is an item in the cart that has not yet been purchased, when the user goes to the page to add another item, display a message telling the user that he must finish purchasing the item in his cart before starting a new order, with a link to the cart. So, my questions are these:

Hi guys, noobie here having a bit of trouble with the Login form, here's the code i'm using to override the standard login form:

I was just following the module tutorial for Drupal 5, but that seems to be incompatible with Drupal 6.

http://drupal.org/node/82920

Is there a tutorial for module development with Drupal 6? Maybe a simple template to begin with?

Hello,

I thought I'd start a topic about this so that people can share there knowledge and advice, while others can learn.

Since the number of facebook users is growing exponentially I notice that the users of m site are constantly complaining about user-unfriendliness and they are always evaluating it in comparisson to facebook. So... which modules and tweaks do you think I would need to get the following effect:

1) On drupal's user profile page there is a default user picture. Undermeath it, or in it's corner there should be a small button "edit" or "upload". I have noticed that these 3 videos http://www.youtube.com/user/BoarK have acomplished something like this using SWFupload. But my suspicion is that he is using some other modules as well.

2) User picture in drupal comes in 1 size only. But how can I make it like in Facebook, where you get 3 different sizes: 200px width for the main profile page, 110px width for the listings, group members, comments, etc and 50px width for private messages. I noticed that there was a whole tutorial about how to use ImageCache for profile pages at Lullabot with loads of comments and scripts, but none of them turned out to work 100% because the default picture would disappear.

I need to create a variable that increments each week to the following Saturday, and then append the variable to a the title of a views block. So the title would be "Weekly Listing $Saturday_date." I plan to use block.tpl.php to call the variable. So my question is should I create the variable with hook_cron, or could I use phptemplate_variables to create it, or is there another better way? Thanks.