2: Nope, they were just created with the universe, they are the caretakers of it, not the creators of everything. They remade worlds, but they did not make them in the first place.
3: No, imprisoned. And this was with all the titans and their minions working together in a massive war did they manage to finally bind them, and with great losses for the Titans. The Titans nearly lost too, but what turned the tide was they shattered the bonds between the mortal realm and the elemental plain, imprisoning the Elementals. And Sargeras is 1 titan, and a lesser one at that. The shattering of Gorshalach made Sargeras lose most of his power, now his main power is in the Legion which would still be crushed by the Old Gods alone, much less with their servants.