1.
- Adium - Fantastic chat client that has about 10 different protocols including msn
- AppZapper or CleanApp - for deleting programs the easy way
- Aurora - Good alarm clock that can use your iTunes library and playlists
- Cocktail - For customizing some of the hidden features in OS X
- LiteIcon or Candybar - Change icons the easy way
- Speed Download - Download Manager
- Toast - Fantastic for burning DVD's
2.
Just play around, you can't do much wrong but look at some mac forums and you can always catch up some sweeeeeeeeeeeeeeeeeeeet stuff from them.
3.
There are plenty of applications that could handle this, from pages to text edit with word stuffed in the middle, it really depends what you want form the application.
4.
There is a way, but i forgot what the application is called. let me think on it.