Upgrading Drupal

OK, as a newbie to the Drupal world, I follow instructions to upgrade my Drupal installation. This installation was created by someone else, so I am not familiar with all the modules it uses, but I can follow instructions. What follows are my frustrations with the process of upgrading Drupal. These are meant to be constructive critiques, not knocks on the great tool that Drupal is.

Very strange. I have version 6.6. I downloaded drupal6.9 from: http://ftp.drupal.org/files/projects/drupal-6.9.tar.gz.

I backuped my database, backuped sites, modules and files directories. Removed all files from my drupal site. Upload all new files for drupal6.9. Uploaded sites, modules and files directories. And runned xxx/upgrade.php.
The version told me, there is no update available (what is de correct version number of drupal 6.9?). And ik also shows 0/0 updates done.

After upgrading a multilingual website from drupal 5.15 to drupal 6.9 with custom theme. I've been banging my head against the wall with language problems. After upgrading my prefixes don't work anymore as they used to, and no matter what I try, the $language->language is always the default website language.

I have three languages and they used to work on drupal 5 with prefixes, like http://example.com/en, http://example.com/fi, http://example.com/zh-hans

Drupal 6.9 seems to use the prefixes as "part of the url", and not as language prefixes.

For example:

Drupal 5.15: if I go to http://example.com/[language prefix]/node/6 it shows the correct information without depending of the prefix (it can be whatever language and it only affects to site layout but not to the content)

Drupal 6.9: I can only view the node by http://example.com/node/6 and if I add prefix before node I always get "page not found"

Settings I've used:

- On Site configuration > Languages: Path prefix only
- On content types and workflow settings: Enabled, with translation

I have newest stable i18n-module installed.

upgrading Drupal 6 update.php hangs when updating system module.
The update process was aborted prematurely while running update #6008 in system.module. All errors have been logged.
An unrecoverable error has occurred.
user warning: Table 'menu_router' doesn't exist query: DELETE FROM menu_router in menu.inc on line 2288.

The table doesn't exist in my database. I am assuming the update is supposed to do this but it seems to have failed.

I can't really do anything when this fails. I can't login to access any admin pages and can't get to any other pages.

When i upgrate my drupal site from 5.x to 6.x, Many of the problems encountered. I have installed more than 30 modules. I want to know how to deal with this modules,uninstall or delete? I have download any of them which have 6.x.

We are on Drupal 5.x and have the Taxonomy Access Control (TAC) module installed. The only supported official release of the TAC module is for Drupal 5.x.
I see there is a TAC module in Development mode, for Drupal 6.x, but we would rather wait for an official version, so we have not gone to Drupal 6 yet. http://drupal.org/project/taxonomy_access

Does anyone have an estimate of when the TAC module will have an official release for Drupal 6?