[GRASSLIST:4383] Jeeping & fixing maps

[Dave Nathanson]

Hi GRASSers,
I spend my weekends exploring the Southern California USA deserts. I've 
come to realize that even though I buy all the non-urban maps I can find, 
most of them are wrong, or at least they don't agree. Or some roads have 
been erased for political reasons. So I want to fix these maps for my own 
use. I enjoy this exploring & data collection. 

I have a 4 wheel drive Jeep, a Garmin 48 GPS, an external antenna, a 
wonderful traveling companion, and a Macintosh G4 desktop Computer 
running Mac OS X (based on Free BSD). I plan to start with 24k DRG TIF 
maps I can download FREE at:
http://data.geocomm.com/catalog/US/61069/1991/group1-3.html
I also want to scan old maps I have, and add them as different layers, to 
see how well they match up against other newer maps.

My goal is to use software that can either read my data from the Garmin 
handheld gps, or a text file. I want to import both waypoints (preferably 
with the associated icon) and the track (which often describes the trail 
I'm wanting to map). I'd prefer a mapping software that supports layers, 
such that I can put different types of map data (paved roads, trains, 
waypoints, waypoints from last year, hand drawn trails, the gps track, 
etc) each on different layers, which I could hide or show. Ideally, I 
should be able to print any area of this map easily, on multiple letter 
sized pages if desired. 

Is this stuff that GRASS can do? 
Can Grass:
  read data directly from the GPS unit? (at the end of the day).
  let me draw on the maps?
  support layers?
  show/hide various layers?
  import a text file of gps track or waypoints?
  print a selected map area to several letter sized pages?
  Print a selected map area shrunk to 1 page?
  Do all this from a GUI?

Am I looking in the right direction? 
Any/all input appreciated. 
Thanks!
Dave