Depends how you define luck - true luck, toss of the coin stuff, no, they can't be, but generally regarded as being lucky in life, yeah, then they probably are.
Optimism (or pessimism) can be a self-fulfilling prophecy. If you are optimistic, your body language will give others the impression that you will succeed - or if pessimistic, the opposite...
No, but if somerthing fell on an optimistic person's head, they'd probably utter a swear word, smile and carry on. A pessimistic person'd be more liable to moan about it and to consider themselves even MORE unlucky! : )
Yes, Ice.maiden is right, some people can just bounce back, and others can't, it's all about whether you see you glass as being half full, or half empty, if you see what I mean!