I need clarificiation

[rsf316]

I will admit, the last time I have read a comic was probably 15 years ago, but I love watching all the super hero movies and television shows that come out. So I watched the trailer for Age of Ultron (looks pretty awesome) and noticed that they are adding in 2 more heroes who are Scarlet Witch and Quicksilver. I wanted to know all about their powers and abilities and all that stuff so I looked them up. I saw that they are twins and that their father is Magneto. This is where I need clarification. If they are the children of Magneto, that means that the Avengers World and the X-Men world are the same (and assuming Spider-Mans). So in the first Avengers when Loki's army came into New York, or in X-Men: Last Stand when they were battling Magneto's army on the island, why didn't they help each other out? Was it like an lolnahfuckyou or do they technically not share the same world and everything is getting all messed up? Again, I'm not deep into comics so I have no clue what's going on so this may be a stupid question.

If you could help clear this up for me that would be pretty awesome, thanks.

Bonus: If anyone feels like going the extra mile and trying to explain to me both how Logan got his metal claws back in the Future part of Days of Future Past and how the Mutant Class Level specifications go in the movies, that would be sweet.

Thanks

AND if Quicksilver is Magneto's son, why is he only like 5-8 years younger then him in Days of Future Past?