Yes, they are, but you have to take ownership of them to add them to your collections.
No because they came out after giants
Yes
Of course.
Giants is the second game of Skylanders. Your current Skylanders can still work for Giants. There will be bigger figure and characters you can buy and new story.
yes they do
no you cant
Yes, you can.
No, you cannot play with Skylanders Giants on Skylanders Swap Force. While both games feature similar gameplay mechanics, each installment has its own unique characters and requirements. You can use Swap Force characters in both Swap Force and Giants, but Giants characters are not compatible with the Swap Force game.
No or maybe hasn't been confirmed yet. But if they do, make sure that you look out for any Skylanders Giants news
no, you cannot use skylanders from skylanders sypro's adventure
yes
yes there is going to be a skylanders 3, it is confirmed in the credits of skylanders giants