Where can I get these Unix applications ?

Xrolodex - ftp://sunsite.unc.edu/pub/Linux/apps/reminder/rolodex/
Addressbook - http://red.roses.de/~clemens/addressbook/
kab, kmail, kjots - http://www.kde.org
WebAddress - http://www.suse.de/~bb/WebAddress/
Plan - http://www.IN-Berlin.DE/User/bitrot/plan.html
Netscape - http://www.netscape.com
Xfmail - http://burka.netvision.net.il/xfmail/xfmail.html
Ghostview - http://www.cs.wisc.edu/~ghost/index.html
Efax - http://sunsite.unc.edu/pub/Linux/apps/serialcomm/fax/
Ksendfax - http://www.sad.it/~jug/ksendfax/
KOrganizer - http://devel-home.kde.org/~korganiz/
StarOffice - http://www.openoffice.org
Lpkg - http://vyx.net/~philz/

Where can I get these Newton applications ?

Sloup - http://www.kagi.com/weyer/#sloup
Newt's Cape - http://www.kagi.com/weyer/#NewtsCape
ViewMP - http://www.imageguild.com/chuma/newtonmad/programming/viewint/Viewmp.htm
Pour - http://cdrom.amug.org/http/newt/newton.html

Check also The totally Newton Archive, Newtonville, the Newton Reference, Newtonware, Planet Newton, and the ULTIMATE Newton for a complete summary of Newton related software.

Where can I find more informations about Newton and Unix ?

You can find a complete summary of Linux software at the Linux Applications and Utilities Page. For more informations about Newton and Unix look at the Newton and Linux mini-HOWTO.