Module development and code questions

I am building an external php script that interfaces with drupal. I am looking to maintain some of the drupal functionality - mainly the blocks from my theme. presently I am including only common.inc - this allows me some functionality (I can tell what user is logged on etc. but I would like to continue to display the navigation / logon block as well on my external script.

What is the "->" operator? What does it do? I can't find a reference that describes what -> does in any of my php texts and I can not find it on the web either.

Can someone clearly define its functionality for me?

Thanks!!

Sadian

has anybody updated the feedback module to 4.4?

I was wondering is there any tutorial available on writing modules in drupal to new users .It will be really helpful for newbies like me to start writing modules .I want to write a course module for my website . I can write code in php ( not an expert ) .I want some help to start writing a module .I really apperciate if any one can give me some guide lines .
Thanks
Drupal Newbie

I have created a module which adds features to event, but doesn't add nodes of its own. I have added a table which includes the node id. When a node of type event is deleted, I want to delete all rows in the new table with the corresponding node id. How do I do this?

Rows should also be deleted when a user is deleted.

How does Drupal track sessions? Is there any information available on how this is done with drupal? I am familiar with php sessions but have been able to nail down how drupal uses it.

Thank you,

Sadian