No, it was destroyed in the 1st age in the Silmarillion. The Lord of the Rings happens in the 3rd age.
Yes, specifically it is the fortress of the Lord of the Rings: Sauron!
Yes, Dol Guldur is a fortress in Mirkwood that Sauron occupies in spirit but it is destroyed and he flees back to Barad-dûr in Mordor.
Barad-dûr in Mordor. Dol Guldur in Southern Mirkwood.
Sauron .
Sauron was played by Sala Baker.
The Lord of the Ring is Sauron, there is no other Lord. But the first ring bearer that was not Sauron was Isildur. The first Lord of the Rings book and movie is 'The Fellowship of the Ring.'
The Dark Lord in The Lord of the Rings is Sauron, a fallen Maia (demigod). There is also Saruman, an Istari/wizard corrupted by the lure of power offered by Sauron.
Sauron's land is Mordor in the east of Middle-earth.
Sauron
Sauron, the Mouth of Sauron, Saruman, Nazgul, Grima Wormtongue, Gothmog, and the Orcs.
No. Sala Baker played Sauron's physical appearance in the Lord of the Rings movie, but was a body actor only. Sauron's voice actor was Alan Howard. In Sauron's appearance in The Hobbit, he was acted and voice acted by Benedict Cumberbatch.
There are no fairies in Lord of the Rings. There are elves, hobbits, men, dwarves, and wizards, as well as a dark lord (Sauron).