Skyrim DLC content

No you cannot get DLC content for free illegaly but if you want you can play mods that are large enough they could pretty much be there own content. Like Moonpath to Elseweyr is good example

Moonpath to Elseweyr

or Falskaar on the Skyrim Nexus

EDIT: Also you can search for great Quest mods there are quite a few on workshop but alot more on the nexus

Nope.

Oh silly you. Of course not. And technically, if it do exist then it won't exactly be "official", wont it? But there are two that significantly expand the already expansive worlds: Wyrmstooth and Falskaar. Though I haven't played any of them--too busy applying nude mods :p

sex mod+nude mod is all you need.

I tried this like a year ago for crossbows. Theoretically, you could make a mod to give you crossbows, but the player animation for using any item is stuck to sword/bow/ect. So no one bothered to create a glitchy crossbow mod.
And for missions. I do not know if anyone recreated any specific ones, but I guarantee you that no one went through and redid all of them.