There are many scripts try one of these

b2evolution
Nucleus
pMachine Free
WordPress

Thanks

If you don't plan to spend a lot of time customizing your blog, I'd recommend Typo 4.0.x, it uses ruby on rails, is very easy to install, and protects against comment spam automatically.

I've tried Typo3 half a year ago. It's hard to learn and will cost you long learning curve. If mambo/joomla or xoops cost you one week time, then typo3 cost you 2 months......

Wordpress is my favourite tool by some distance. Plenty of support from the userbase and there are stacks of free plugins/themes available too.

An easy question, but very difficult to answer. I assume you have already a working site that you are happy with. If you have no plans to change that site drastically or move the content to a CMS, I would suggest a specialistic blogging product like WordPress.

If you however are not entirely happy with your current site and want to redesign it in the near future, a broader CMS is better which has blogging as a feature or a plug-in. This is however a question we cannot answer. But speaking from my own experience, once you get used to the easy way you can add new content to a blog, you definitely start thinking if the same maintenance concept can be applied to your whole site.

drupal is an excellent tool you can use to set up many small websites. it has blog support and several other nice features.

An easy choice is ThingaMaBlog. No on-server SQL, Perl, PHP, or other cgi programs required. All you need do is assign each blogger a directory/folder for their blog. Blog templates, data files, etc are all stored on the users computer and all they upload to the server are html files (and pictures .png, .jpg, .gif, .bmp - etc.) using FTP protocol. You then only need to set up a FTP server giving them access to their directory as their home directory. Their ftp uloads are contained entirely in their directory/folder with the pictures in a media folder contained in their folder. They only need write access to create the necessary folders within their home directory/folder.

i use wordpress kinda easy for me

For business blog typepad is pretty nice.