Ok, I think I’m starting to get a good grasp of the rules but I still have a number of questions:
1. Can characters with STR 0 be declared as attackers / defenders?
2. Can 0 STR characters use/trigger their abilities? For example, could core set Robert Baratheon claim his 2 power for renown? Could a core Robb Stark with STR 0 still attack and use his ability to kill a character?
3. Until when exactly are characters considered to be “participating” in a challenge? And to what framework action do responses that depend upon you winning a challenge actually respond? Could Brienne of Tarth (“While Brienne of Tarth is participating in a challenge, opponents cannot trigger effects.”) prevent core Robb Stark or Wolves of the North Khal Drogo from triggering their abilities? Or would Brienne already not be participating at that point?
4. What exactly does the text box include? Does it include traits and key words?

Fancy B said:

Yes. The only requirement is a proper icon.

Remember that you need at least 1 total STR and at least 1 character to be able to win / oppose a challenge.

Fancy B said:

Yes. See above.

Fancy B said:

Challenge ends after its resolution. However you may still use such effects later (see cards like "A Lannister Pays His Debts") in the case of passive and response effects, so effectively characters are considered to be participating until the end of framework action window. Thus, I think Brienne stops responses also. I may be wrong though.

Fancy B said:

The text box include: all of the text on a card including traits, keywords and abilities plus gold, influence, and initiative modifiers.

Rogue30 is correct. A challenge duration lasts all the way through Responses to winning/losing the challenge, etc.

I guess that means Brienne is pretty awesome then. I am still a bit confused about the timing though. Each step in the flow chart on the FAQ (1.Determine winner of challenge, 2.Challenge result is implemented, etc.) is considered to be its own framework action right? If responses are played after renown is rewarded, does that mean they are technically responding to step "4. Renown is awarded"? Or is each step supposed to be part of one big framework action? To what framework action are save responses supposed to be responding? I think I'm starting to confuse myself...

Fancy B said:

Yes. See the arrows flow at chart - page 17. Each step/event must resolve before you continue to next. Whatever you want to respond, you play it after framework events and after passive effects.

Fancy B said:

Save and cancel responses are special - they must be played at step 2 (the same flowchart, page 17)

For example "Red Vengeance" (contains magic word: cancel) is played immediately after initiation of framework event "2. Challenge result is implemented" before its resolution, thus canceling it. Hope it helps.

More like GentlemanAndaScholar30....Thank you; this has helped me out a lot.

Fancy B said:

If you read ktom's answers you will learn quickly

The timing trick to framework actions is that each of the individual framework events cycle through their own Steps 1-3, then move on to a common Steps 4-6.

So in the challenge resolution window, the progress isn't 1-2-3-4-5-6 so much as 1a-2a-3a-1b-2b-3b-1c-2c-3c-1d-2d3d-4-5-6. So the passives and Response opportunities to all of the framework actions (a, b, c and d) are open/available at the same time.

Oh, I did not understand the timing at all. So to clarify: each framework "action" is actually comprised of one or more framework "events." And each framework event cycles through steps 1-3 of the framework action before going on to steps 4-6 (where passive effects and responses to any of the framework events can be played). Thanks ktom, you have just helped me to have one of those awesome lightbulb moments. Unless of course what I just said is actually wrong...

Fancy B said:

Perfect. That is exactly right.

This particular trick of the game's timing in framework windows is one that is often overlooked, but ends up being very important to understanding things, particularly revealing/resolving plots and resolving challenges.