BLIZZARD: Plosive meets slithery thing (we hear) on Caradhras.
RINGBEARING: ABBA song swallows little Beatrice. It’s exhausting!
ORCS: Oo, they’re awful!
NEEKERBREEKERS: Cousins of Vogons? They torment with onomatopoeia!
WATCHER IN THE WATER: Submerged stalker, or just a wet TV addict?
EMYN MUIL: Lovable rugby player loses surname and liquid, but gains an equine hybrid here, we hear!
AMON HEN: Grumble about chicken? Here?
THIRST: ‘Lotsss of thisss in Mordor, my Preciouss!’ (he gasped).
HUNGER: Do this only for a taste of justice or a world of truth. (The twin of the last clue).
A: Nice place? No, a slum. Messed up.
NAZGUL: Breathing apparatus swallows map-book, in confusion. (They’re so bad at finding people, you’d think they had, too).
HORROR OF SHELOB: Terror of Cirith Ungol.
AMON AMARTH: Morning marathon around (or rather up) here – and the final one.
R: To hear these might well dement. Perhaps they were played to Frodo in Cirith Ungol?
TREE-ROOTS: Much harder than feather-beds!
HOMELESSNESS: Hateful road brings epiphany of danger – and this.
ARAGORN'S SINGING: Beren and Luthien, brought to the camp-fire by this.
DEAD MARSHES: Inanimate bogs.
PASSWORD: BRONWE ATHAN HARTHAD ('Endurance Beyond Hope' - a name given to Frodo, post-quest, by Gandalf, in an early draft of 'The Lord Of The Rings.')
THEME: Things or experiences endured by the Ringbearer (with number 14 as a trick question/odd one out).
I don't think of it as obscure, because Frodo is not an obscure character. Also, since he's my favourite literary character, not much that's been written about him is obscure to me.
The A clue is much easier than you are making it. As the theme is endurance/suffering, and this is not one of the 'jokey' answers, think about which experience it might refer to.