Regarding gounds...The best ground in the vehicle is the body its self. The obove problems are very common examples of bad grounds..... As for using seperate grounds for communications vs. other equipment, that will not make a difference...however, you do want to use seperate hot feeds and fuses.
One of the best ways to beef up your electrical system and prevent ground and feed issues is to power all of your high current gear off relays. The relays should be feed directly (via a fuse or CB) from the battery. You would be surprised how much brighter your headlights are if you use the headlight switch to energize a relay that in turn engergizes the headlights.
The second trick is to run a heavier ground wire from the battery to the body.
On my jeep I take the hot feed for all accessories right off the hot side of the starter solenoid. My ground then has extra heavy wires going to both the engine and body. One last thing...its a good idea on any vehicle over 10 years old to pull of both power and ground connections and clean them. Also, examine any crimp connections and look for oxidation. I usually solder mine.
John......southern CA
84CJ7, 3"lift, 32"BFG, 4.10's, ARB Locker, Solid Axle's, Durabak