Making a classic Final Fantasy/RPG maker type of RPG is not that hard, there are plenty of examples out there.
On the other hand, games like Final Fantasy Tactics, X-Com or Fallout 2 etc, which have a grid system, is much harder to make. I don't know if Construct 2 is capable of making one.
Yes it is. You would just have an array that corresponds with each grid cell on the map for tracking placements. But this type of game gets incredibly complex and would be best served with a team.
As far as RPG's go, I think mine (Courier) is coming along nicely. Granted, it does not have a combat system (intentionally), but you still have the large, story-rich areas, quests, abilities, magic system, inventory, npc's, etc. C2 could handle more than what I'm doing, but I couldn't by myself, of course.