Advance OpenStreetMap surveying with GTA04?

[Mayeul Kauffmann]

Hi,
I'm looking for a handled GPS device for advance OpenStreetMap surveying
and I hope the GTA04 Phoenix would do what I need.
A few words on the project: 80-day mapping party, hiking, crossing the
Alps (Summer 2012),  20 people involved (many of them for just a few
days). Sleeping in Alpine Huts. Hiking and surveying during the day, if
possible OSM editing in the evening (with a netbook).

I need a GPS receiver to:
1- find our way
2- know what is already in OSM database (with full tags)
3- take pictures with advance surveying data (heading, precision)
4- save track with advance surveying data (precision)

For 1 and 2, I am aware of some OSM-related software that should do it,
see http://wiki.openstreetmap.org/wiki/Openmoko 
Still I do not know how well the GTA04 hardware is integrated into this.
For 3 and 4, I need precision-related NMEA fields, as many as possible
(at least HDOP -Horizontal Dilution of Precision-, other data like
number of satellites, signal strength... is bonus). Saved in GPX and/or
in exif. If possible: get a music alert when precision is low; have HDOP
ready to show as circles in JOSM.
For the picture, I need to save lat-long position + heading (angle to
North) of picture (in exif or elsewhere; tilt is bonus). Post-processing
is an option for position but probably not for heading and tilt.
How good are the pictures? Are there online examples of pictures taken
with the GTA04?

Extra questions: 
If something is working easily on Neo Freerunner, is it then 100%
guaranteed it will work on GTA04?
Anyone using JOSM on GTA04 with surveyor plugin, taking live position
from gpsd? http://wiki.openstreetmap.org/wiki/JOSM/Plugins/Surveyor 

If the above is already possible from a hardware point of view, is the
software doing this already available? Or, would it be easy to
implement? Ideally HDOP and the like should go into both exif of the
pictures and gpx track, but post-processing (gpscorrelate or the like)
is OK. I have no problem writing a few pages of (bash) script to pipe
outputs or combine several command lines tools.
However, hacking hardware drivers or working at very low level (read:
close to hardware layers) is beyond my knowledge.
More on the project here:
http://www.outdoormaps.org/
http://wiki.openstreetmap.org/wiki/ViaAlpina

Thanks for reading. Looking forwards to reading your answers!
Mayeul