Set configuration value $conf['debug_info'] = 1 in file kb/admin/config.inc.php, then you can see real sql errors and all php errors. Make sure you properly edited(adjusted) file kb/admin/config.inc.php

All languages files are in kb/admin/lang/[lang]/ directory. Open your language folder and make all necessary changes.

Search functionality is provided by MySQL full-text searching. This is a natural language search that allows you to type in a question or regular sentence that describes the information you are looking for, and then uses programmed logic to determine the keywords in the sentence.
See here for details Boolean Full-Text Searches.

Optionally you can set KBPublisher to use Sphinx search engine. It is a full-text search engine that provides fast and relevant full-text search functionality.
See this article how to enable it.

The minimum and maximum lengths of words to be indexed are defined by the ft_min_word_len and ft_max_word_len system variables.
How to change ft_min_word_len 
Fine-Tuning MySQL Full-Text Search
Full-Text Stopwords

To translate to other language you should copy directory kb/admin/lang/en and rename 'en' to translated language.
Made all necessary changes in .ini files and in config_lang.php
Set your language in $conf['lang'] variable in admin/config.inc.php
($conf['lang'] = 'your_language_folder_name';)

We have made some special utilities, it will display some help information:

• http://your_domain.com/kb/admin/lang/test_language.php
• http://your_domain.com/kb/admin/lang/display_language.php

You can find available localizations in download section.

Instructions can be found in this article.

For now so called "Search engine friendly URL" works only on Apache web server.
It should work automatically if your Apache is installed with mod_rewrite enabled.
Please read here for more details

MySQL is not enabled by default, nor is the MySQL library bundled with PHP. In order to have these functions available, you must compile PHP with MySQL support.
PHP manual - MySQL

Set conf['debug_info'] = 1 in your_kb_installation_directory/admin/config.inc.php. It will  display  an error if  you do not have MySQL extension enabled.

No. Currently KBPublisher supports only MySQL.

Sure you can. The process is like for adding image to article. Use "Insert/Edit Flash" button from HTML editor toolbar.
Tip: you can add any HTML inside the content page.

The most likely cause is that your PHP installation does not have GD. Check if the GD library is installed with php and install it if it is not.
Information about GD and instructions for installing it can be found on the PHP site at http://www.php.net/gd. 

Make sure you set up Scheduled Tasks.
See Setting up scheduled tasks and Track scheduled tasks articles for details.

Try the following steps:

1. Run setup wizard from the start, click "Cancel" to start it over.
    
2. Make sure cookies are allowed in your browser.

3. Check out your session.save_path variable 
   and make sure directory is writable and have enough space.

   http://php.net/manual/en/session.configuration.php#ini.session.save-path

Error message/code:

PHP Warning: Undefined ...

Description:

PHP Warning stops script execution.
The reason is that, in PHP.ini, log_errors=on but error_log is undefined.

Solution:

In PHP.ini set error_log = syslog