Installing of Joomla! 1.5 is pretty easy. We assume you have set-up your Web site, and it is accessible with your browser.

Download Joomla! 1.5, unzip it and upload/copy the files into the directory you Web site points to, fire up your browser and enter your Web site address and the installation will start.

For full details on the installation processes check out the Installation Manual on the Joomla! Help Site where you will also find download instructions for a PDF version too.

You indeed can change the Menu Item's Type to whatever you want, even after they have been created.

If, for instance, you want to change the Blog Section of a Menu link, go to the Control Panel->Menus Menu->[menuname]->Menu Item Manager and edit the Menu Item. Select the Change Type button and choose the new style of Menu Item Type from the available list. Thereafter, alter the Details and Parameters to reconfigure the display for the new selection as you require it.

No you don't. Versions of MySQL lower than 4.1 do not have built in UTF-8 support. However, Joomla! 1.5 has made provisions for backward compatibility and is able to use UTF-8 on older databases. Let the installer take care of all the settings and there is no need to make any changes to the database (charset, collation, or any other).

Yes it can! This is a significant security improvement.

The safe mode limits PHP to be able to perform actions only on files/folders who's owner is the same as PHP is currently using (this is usually 'apache'). As files normally are created either by the Joomla! application or by FTP access, the combination of PHP file actions and the FTP Layer allows Joomla! to operate in PHP Safe Mode.