One more question: can bear island target littlefinger (the lannister/stark version) since it has stark in it? or is it also cosidered lannister so it can?

No, you can't target him... He is a Lannister, but he is a stark too, so the restriction applies and you can't kill him...

Essentially, it doesn't matter how many other House affiliations the card has - so long as it has the Stark affiliation, it counts as "Stark" and is therefore not considered "non-Stark."

On the plus side, if you have Littlefinger in your Stark deck, his Lannister affiliation doesn't "turn off" Bear Island, either..