Check out the included tactical game example which has a skill system similar to the one you descrive (including skipping a turn). It is in Maps/SciFi/Jungle_Raid. I’ve made a video describing some of this here.
Your second question only seems to relate to networked multiplayer games, and probably only to MMO-style games at that. ATBTT does not currently have networked multiplayer support and even when it does (planned for the next update) I have no plans for adding anything related to having persistent worlds with large numbers of players. Anything like that you would have to add yourself, though I’ll provide input to the best of my ability when you get to that point.