We got turned back from the Zobh route on the way to Iran in Jan 2006.
You need a permit for this route.
We went via your 'route 2', there this is a section of about 70ks of easy dirt roadif i remember correctly. It was a great ride!
It is a long days ride from Quetta to the border, so you must either cross the night before then stay at the border(theres a hotel right next to the border), or come through first thing.
I dont know anything about the 3rd route.
Please take note that after we were turned back from the Zhob road, the same police told us to go to DG Khan to find somewhere to stay for the night(It was the more northerly of the to D- Khan's, think it was DG khan). When we got there all the hotels turned us away saying the government had made an order that no foreigners were allowed to stay in the area as there was a lot of Al Quaeda activity. This meant we had to ride through the night to get over the indus to an area where we could get a room.
Id check the situation at the border if possible as you dont want to be riding around at night etc if you can avoid it.
The area was actually fine and i absolutely loved Pakistan more than anywhere else ive ever been, so dont let this bit of government meddling worry you. Its just a pain in the backside if you get caught out by it.
We managed to not pick up a police escort as they can be very dull ive heard. One guy we met got escorted all the way to Lahore.
Look like you know where you're going and hope they dont decide to help!
Have a good one.
chris