FYI, as the N9 is based on Debian, most of the programs you mentioned should run on it. I use OpenOffice.org and The Gimp occasionally on my phone if I really need to (the 3.5" screen is not ideal but it works).
Phones that support USB host (or USB on the go) could have a keyboard / mouse. I've done that with my N900. I don't think the N9 supports USB host out of the box but I bet some enterprising hackers will get it working. The N9 also has TV out (but not HDMI).
You could, alternatively, connect the keyboard / mouse via USB. Nokia's N8 has USB host and HDMI out but runs the Symbian platform. Here's a demo of the N8 connected to a TV & a keyboard / mouse: http://dailymobile.se/2010/10/07/nokia-n8-hdmi-bluetooth-key...
