The ears...

[Sharkû]

This is a fairly standardized answer, sorry if any points previosly made by other posters are repeated unnecessarily.

The reference to pointed ears mentioned above is taken from Letter #27, 1938 (!):

"A round, jovial face; ears only slightly pointed and 'elvish'; hair short and curling (brown)."

. This obviously does not say anything about the shape of the ears of the Quendi. This description of Bilbo was aimed to be understood generally and by the public, Tolkien’s Quendi were at that time not commonly known, however. The ‘elvish’ thus refers to those ‘fairies’ of common European folklore, from which Tolkien took great pain to distinguish his Quendi, such as in the “Guide to Names in Lord of the Rings”: “The Elves of the mythology of The Lord of the Rings are not actually equatable with the folklore traditions about ‘fairies’”. It would be interesting to know whether the idea of pointed hobbit ears was not abandoned as well in the mind of their creator later on.

The often cited article in the Etymologies (HoME V) should here be given in full:

„LAS(1)- *lasse leaf: Q lasse, N lhass; Q lasselanta leaf-fall, autumn, N lhasbelin (*lassekwelene), cf. Q Narqelion [KWEL]. Lhasgalen Greenleaf, Gnome name of Laurelin. (Some think this is related to the next and * lasse 'ear' . The Quendian ears were more pointed and leaf-shaped than [?human].)” (HoME 5, Part Three)

This is a doubtful argument for two reasons. For once, this quote is to be dated long before the publication of the Lord of the Rings, that is, 1937/38, and has assuredly been abandoned. On the other hand, the quality of the statement itself is in turn questionable. The use of the comparative form does not denote definitely pointy shape.

The most important argument against pointed ears of the Quendi, is however one that can only be underlined with quotes with tremendous effort, for it extends over the whole of Tolkien’s meta-text and is a central point of the philosophical writings to be found in HoME X to XII. The physiologic nature of Man and Quendi is indeed exactly the same, the only difference is in the fate attributed to the fëar, not in the exterior of the hróar. This is also why Men and Quendi could only be distinguished by their eyes (cf. Tuor, UT), which were indeed mirrors of the soul. The choice of a half-elf would thus only affect the fate of his or her descendants, since the body would be the same in any case.