1) You only need a PPL
2) CPL only if you are going to do parachute jumping, survey work, glider towing, career flight instructor, light twin stuff etc. ATPL for any passenger flying or cargo. For the sake of 3 exams, its not worth not doing the full 14 ATPL's
3) It looks good, but it won't be the defining thing though. Total hours and type of hours logged are far more important as is a type rating. Its all about eliminating percieved risk for the airline and keeping their costs down. Inexpericenced pilots need a lot of resources ploughed into training them.
The biggest hurdle you will encounter in Europe is your name on the top of a CV. Not being harsh, I'd be surprised if that hasn't crossed your mind already.