1. No
2. No
3. It will put loot assigned to you (all of it if you're the only one killing the monster / not in party share) directly into your inventory. You can use @autoloot 0-100 to choose different ranges. By default it's set to 100 (which will pick up all items with a 100% drop rate and less). If you ONLY wanted to an item with a 10% drop rate, you could use @autoloot 10.
to unlock a location, you need to talk to the "save npc" (in red) that's in each listed location, pay a fee (varies depending on which place it is) and after that, you can start using warp npc to go to those dungeon. Most of the time, the save npc is near the entrance of a dungeon or near a kafra for cities, but there are exceptions. For example, biolab save NPC is back in floor 1, even though the quest lets you enter the biolab in floor 2 through the sewers. Turtle dungeon save NPC is near the entrance to floor 2, and not the place where you get off on to the island.