• There are no plans to give the Protoss any healing abilities, especially since their shield regeneration rate when out of combat, is more than twice the rate of the original StarCraft.
• Explosions will not be able to push units, but they can destroy doodads. In fact, destroying certain doodads will be vital on certain maps, to get access to expansions or other strategic locations.
  
• Furthermore, explosions will not be able to push units because it would affect gameplay and balance negatively, in having units be knocked off cliffs, be stuck in unplanned locations, or ultimately have units disoriented where the player cannot control them.
• With a finished concept piece, it could take from a few days to a few months, to create it for the game. Much of this time depends on the priority of the unit amongst other development goals, as well as the iterations necessary to perfect the unit.
  
• The Zerg Baneling is an example of a unit that took only a few days to complete after the concept, whereas the Protoss Stalker has gone through several iterations, and has taken four  to five months.
• We are still heavily in the development phase of StarCraft II, thus none of the units on the website are 100% final. We are also still testing out several new units, abilities, and mechanics, to create the most fluid StarCraft II experience.
• Protoss gain nutrition from sunlight, or at a pinch, moonlight (which is just reflected sunlight anyway) by absorbing through their skins. They can go for extended periods without absorbing sunlight. What little moisture they need is also absorbed through their skin.

Via Battle Net