Upgrading Drupal

I've followed the instructions in the video from http://learnbythedrop.com/drop/70 to upgrade. I'm up to the point where i need to go to upgrade.php

when i point to my upgrade.php, I get a 403 Forbidden Access error. The only thing that is really different from his method and mine is that I extracted all the files from the tar.gz into my directory. I instructed it to rewrite over all the files. I believe all the permissions are 755.

I have 5.2 running with a custom theme and lots of modules as my site gets bigger, I wanted to add a video or two. Can anyone tell me if it would be better to upgrade first?
If so how can I keep what I have built... index.php and what other files?

I'm having problems with my tracker not displaying the comment count correctly. For reference, I have been rebuilding my website due to corrupted tables at who knows where. http://drupal.org/node/323254 is that thread.

My tracker displays everything correctly except comment count, which it displays for everything as 1.0037 instead of the correct number (0, 1, 2, 3, etc). I copied the tracker view and made a similar view: recentForumPosts just for displaying recent forum posts. The query is:
SELECT node.nid AS nid,
node.type AS node_type,
node.title AS node_title,
users.name AS users_name,
users.uid AS users_uid,
node_comment_statistics.comment_count AS node_comment_statistics_comment_count,
node_comment_statistics.last_comment_timestamp AS node_comment_statistics_last_comment_timestamp,
history_user.timestamp AS history_user_timestamp,
history_user.nid AS history_user_nid,
node.created AS node_created,
node.changed AS node_changed
FROM node node
LEFT JOIN term_node term_node ON node.vid = term_node.vid
LEFT JOIN term_data term_data ON term_node.tid = term_data.tid
INNER JOIN users users ON node.uid = users.uid
LEFT JOIN node_comment_statistics node_comment_statistics ON node.nid = node_comment_statistics.nid
LEFT JOIN history history_user ON node.nid = history_user.nid AND history_user.uid = ***CURRENT_USER***

My drupal install got messed up somewhere along the way when I tried to go from 6.4 -> 6.5. I discovered that I accidently copied all of drupal6.4 into the /sites/all/modules folder, and somehow that folder had become an integral part of my install. When I tried to delete it, I got all sorts of errors. I did a search for drupal6.4 in my database, and edited all examples into the proper directory, but it wasn't enough. I've tried a few methods to determine where the errors are in the database, but I'm out of ideas.

Fatal error: Call to undefined function user_access()in /home/my_website/public_html/includes/menu.inc on line 449

I've tried reinstalling back to 6.0 but I"m basically screwed now...

I can't even see my website anymore. Yes, I'm a drupal noob.

Argh.

Hi there,

I´m looking for the filters documentation in order to upgrade one 5.x custom filter to 6.x but didn´t found anything on the docs?

Anyone could point me to the filters section? Thanks in advance, Simon!