I'm a bit confused with some of the combinations that can occur

I'll try to be brief

Seaside Urchin

Response: After you win an Intrigue challenge in which Seaside Urchin participated, discard the top card of the losing opponent's deck. If that card is an attachment or an event card, Seaside Urchin claims 1 power.

Motley Crewman

Any effect that discards 1 or more cards from an opponent's deck discards an additional card.

So my fist question is what is Motley Crewman doing

Is the discard of an additional card a separate action or would it by part of the Seaside Urchin action - If I have both in play and trigger the repsonse on Seaside urchin, 2 cards would be discarded - do I only claim a power if the first card is an attachment

Kraken Tattoo

Response: After a card is discarded from a player's deck, attached character gets +1 STR and Intimidate until the end of the phase.

Continuing the above, when I trigger Seaside Urchin (With Motley Crewman) and have another character with Kraken Tatto attached, would they get +1 or +2 strength

Corpse Lake

Response: After a triggered effect discards 1 or more characters from the top of an opponent's deck, claim 1 power for your House. (Limit 3 times per round.)

As above with Seaside Urchin and Motley Crewman - if the second discarded card is a character can I still claim a power - the second card is being discarded due to Motley Crewman's ability but that ability is passive (no response)

First; some terminology. Motley Crewman is not a passive, it's a constant effect that modifies discard effects. If it were a passive, it'd be "After an effect discards one or more cards from the opponent's deck, discard one additional card".

This same question comes up rather often, so I'll just link you to three previous incarnations of the same thread (all the answers there should answer your questions, and any others that may come up regarding discard scenarios);

http://community.fantasyflightgames.com/index.php?/topic/76861-motley-crewman-discard-scenarios/

http://community.fantasyflightgames.com/index.php?showtopic=65340

http://community.fantasyflightgames.com/index.php?/topic/60422-old-thread-new-question-motley-crew-and-thugurchin/

In short form:

1) Seaside will claim 1 power for each event/attachment discarded by its effect (modified by Motley)

2) You could respond for each individual card discarded. , even if they were all discarded by the same effect.

3) Since it refers to each effect, and only one effect was triggered (Motley crewman modified that same effect) - you will only claim 1 power.

ninja'd

Thanks for the short form update

I did look at the links but there's a lot to read ... I'm just relieived the links didn't point to any of my previous questions

Understanding that something is a constant affect and not a passive is a big help