MrDeath answered most items, just adding a few points for clarity.
Pirate A and Pirate B are sword fighting on the deck of a ship. Pirate A is losing, so he decides to fight dirty and use a maneuver. Because Pirate B is a significantly better swordsman Pirate A decides to maneuver against the environment and kick over a barrel of lamp oil that happens to be nearby. Pirate A rolls *something* against a fixed target the GM decides. In this case I will use Average (+1) since kicking/shoving over a barrel isn't all that hard. Pirate A gets say Great (+4), giving him 3 shifts and creating a 'fragile' aspect of 'The Deck is Covered in Oil!' that lasts a total of four uses.
Regarding duration - there are really only two variations: a fragile aspect lasts for one use which needs to occur relatively quickly after creation; a sticky aspect lasts until something is done to change it. This could be another maneuver action (clean up the oil, throw sand across the oiled deck, etc) or simply scene or time based. Either way, you only ever get one free 'tag'* on the aspect.
Pirate A gets one immediate Tag against 'The Deck is Covered in Oil'. What effect does this have? Or does the Pirate or GM decide it or something? Seems to me that the Aspect could be used either defending against Pirate B or in attacking Pirate B.
See list below. Unless initiating a compel, the tag will provide a bonus to a roll.
Pirate A does his thing. Now it's Pirate B's turn. Pirate B notices (because he's smarter than a turnip) that 'The Deck is Covered in Oil'! and decides to Tag/Invoke/Compel that aspect (whichever one it is) to use against Pirate A. This costs him a Fate Point.
Question 6: When Pirate B uses 'The Deck is Covered In Oil' to enhance his attack against Pirate A.... can Pirate A also spend a point of Fate to use the same aspect to enhance his defense roll? Does Pirate B then get the Fate Point that Pirate A used?
Yes, both pirates may use the same aspect in the same exchange...
if it makes sense. While it may take some fast talking to convince me slippery decks will be helpful for defense there may well be a case where an aspect could be applied to both rolls.
A given aspect may be used once per action / roll. (YS99) So both an attacker and a defender (two different actions) may use it. However, it does need to be relevant to each action.
*Terminology is obfuscated in DFRPG. Luckily FATE Core cleans it up some. Here are some short definitions:
- A 'tag' is an invoke you receive for free.
- An 'invoke' is using an aspect to gain a bonus (usually +2) to a roll.
- An 'invoke for effect' is a compel initiated by a player.
- A 'compel' is using an aspect to change the narrative, forcing it in an aspect related direction.
There are some technical details between invoke for effect and compel which will have people disagreeing with me. They've been discussed enough in other threads.