The GPS - issue (GPS searching forever, no fix, status bar does not even show the gps-icon) can be fixed by wiping the efs data.
This data is stored in partition 13 and partition 14 on the G2/DZ/DHD/MT4G.
To do this you have to get a root shell on your phone (either using adb shell or a terminal app) and then use the following command (as always: do not type the # it only indicates the root prompt in the shell)
If your prompt is not # but $ then first do:
$ suand answer the question of Superuser. (Well you should all know this by now :-) )
# stop rmt_storage # dd if=/dev/zero of=/dev/block/mmcblk0p13 # dd if=/dev/zero of=/dev/block/mmcblk0p14 # reboot
After this you should have your gps back working.
To wipe the efs is general a good idea if you switched radio-firmware or the ril-libs (which might happen when you switch from one rom to another)
have fun - Guhl