There are alternate exits for all bases. Including district entrances, there are 8 total exits to home base I have encountered.
These are there for the exact purpose of preventing "spawn point campers." The ladders leading to each of the districts brings you to an elevated location with no other access point besides the one from your home base; you can survey the area in safety and pick a location and time to jump off.
There are safe areas scattered throughout the districts, only for quest related areas and certain district entrances so far in my exploration. A buff is applied to you, removing the PvP flag and giving you a blue aura. If you enter stealth while the aura is active (you are inside the safe zone), you are granted a speed buff for as long as you remain crouched. Bug or WAI I do not know, but it allows you to move a great distance from a safe zone in a short period of time, all under cover of stealth.
If that is still not enough safety for you, bring some Invisibility potions with a Major Expedition side-buff and pop one before you leave a safe zone.
The only hazardous connections are the Sewer-to-District ladders found outside home bases (in the actual sewers proper). While you are loading into the area, AoE attacks can damage you but single-target cannot. I have not encountered any players attempting to camp these entrances (there are far more entry points to the districts than these) but there have been reports of such incidences.
In the next PTS patch, ZOS is adding a 30 sec invulnerability buff when you load into another area. This buff will be removed when you perform any action. This will solve the issue stated in the paragraph above.
Edit: All areas with PvE enemies in them are PvP flagged. The quest related safe areas contain NPCs and are visited for cut scenes. You can talk and listen to NPCs without fear, as well as watch quest sequences.
The various quests in Imperial City award Tel Var Boxes, which can be opened at any time. They award around 300 stones. Being boxes and not actual stones, they cannot be looted by other players. This is a safe income for the PvP inept.