Actually man Skyrim SE has the 3 DLC's so yes new quests and no it does not contain ads plus when you install mods just use NMM its that simple i am an old player of this game and its still interesting.
Its dumb to continuously make big mods for oldrim and not also for sse it gets annoying when i go to look up a really cool mod like dragon transformation or super saiyan transformation its there but only for oldrim and i get mad when i see that