Not official, but my group agrees that you CAN throw it for all of your flurry attacks. You still have the limit on distance thrown which will hurt fast.
Bonus answer, no. Rapid Shot and Flurry are both full round actions. Two full round actions cannot be combined.
You're able to benefit from flurry's "two-weapon fighting" extra attacks from your thrown shield while it's in flight.
Rapid Shot should work.
I think that this would also apply to brawlers:
A zen archer cannot use Rapid Shot or Manyshot when making a flurry of blows with his bow.
Two weapon fighting is an option you can use when taking the full attack action.
Rapid shot is an option you can use when taking the full attack action.
Just because they are both options associated with the full attack action doesn't mean that you can choose them both at the same time.
You can use the shield with Flurry because you can use a shield with flurry. Flurry also breaks the requirement of needing two weapons when gaining the benefit of more attacks associated with two weapon fighting. It is still questionable if you can gain those extra attacks with a single throw or if you need to throw the shield twice.
I think that this would also apply to brawlers:
A zen archer cannot use Rapid Shot or Manyshot when making a flurry of blows with his bow.Two weapon fighting is an option you can use when taking the full attack action.
Rapid shot is an option you can use when taking the full attack action.
Just because they are both options associated with the full attack action doesn't mean that you can choose them both at the same time.
You can use the shield with Flurry because you can use a shield with flurry. Flurry also breaks the requirement of needing two weapons when gaining the benefit of more attacks associated with two weapon fighting. It is still questionable if you can gain those extra attacks with a single throw or if you need to throw the shield twice.
Zen archer and Far Strike Monk both come out and say Rapid Shot can't be used. Since it isn't mentioned with the brawler, I'd say it does work. Who knows if it's an oversight or an intentional change. Note that the base monk ALSO doesn't say anything about rapid shot and flurry either.
I think that this would also apply to brawlers:
A zen archer cannot use Rapid Shot or Manyshot when making a flurry of blows with his bow.Two weapon fighting is an option you can use when taking the full attack action.
Rapid shot is an option you can use when taking the full attack action.
Just because they are both options associated with the full attack action doesn't mean that you can choose them both at the same time.
You can use the shield with Flurry because you can use a shield with flurry. Flurry also breaks the requirement of needing two weapons when gaining the benefit of more attacks associated with two weapon fighting. It is still questionable if you can gain those extra attacks with a single throw or if you need to throw the shield twice.
I'm with Graystone here that it needs to state it doesn't allow it.
Rapid Shot states it works when one makes a full-attack action with ranged weapons. The brawler can make brawler's flurry as a full-attack action which they can do by throwing the shield, a ranged weapon.It isn't questionable if it's a single throw or not, it has to be a single throw as the returning shield ability specifically states it ricochets off previous targets to hit the next one, shield throw can be performed as part of brawler's flurry, and that the shield returns to the brawler at the end of his turn. The shield has to be in flight during all its potential attacks and not a blinkback belt+throwing shield situation.
Komoda, yes, you can combine TWF and Rapid Shot. There is nothing in the rules to prevent it. Combining TWF and Rapid Shot is central to some thrown weapon builds.
So your position is that:
1) The class/archetype (Zen Archer) that clearly is the best at the ranged flurry can't use rapid shot for the extra attack,
and
2) The base class (Monk) can't use natural attacks with flurry for that extra attack,
but
3) The shield thrower can gain an additional attack through the use of a feat? Can he also use many shot?
Yeah, we clearly disagree. It is my position that the higher damage output (full strength off hand and larger base damage) are meant to stop additional attacks short of special circumstances like Haste and expenditure of Ki Points.
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As to how many throws, my point was, as the OP's GM pointed out, that the ability clearly states:
"If a shield champion has additional attacks from a high base attack bonus, these additional attacks can be ricochets off an earlier target."
Attacks gained from two weapon fighting and flurry are not gained based on high base attack bonus, as required by the sentence above. And yes, since you can use only one weapon (if you want) during a flurry, you can use the shield for all of the attacks. But it is not outside the realm of logic to require a second throw for the second (offhand) set of attacks. If using two weapon fighting and not flurry, it would require two different shields and throws for sure.
Mechanically I would think you would want to throw it again anyway as it would shorten the overall distance to the target and has absolutely no other affect on the attack roll (until level 17). Since you can't reset the range at every point of contact, is there any benefit to the ricochet other than the origin change gained at level 17?