How many 8-letter words are there?

28,420 in the Tournament dictionary, which is the public-domain ENABLE word list. The Broad dictionary adds more.

What is the highest-scoring 8-letter word?

ZYZZYVAS at 44 points, counting tile values with no board multipliers.

No. The page shows the 300 highest-scoring; the pages linked below break the full list down by starting and ending letters.

28,420 words are exactly 8 letters long. ZYZZYVAS scores highest at 44 points.

Showing the highest-scoring of 28,420 words. The pages linked below split the rest into smaller lists.

The dictionary holds 28,420 words of exactly 8 letters. A selection is below, ordered by Scrabble value.

Lengths span 8 to 8. The middle of that range is where the words are: 28,420 of them are 8 letters long.

If you are playing for score, ZYZZYVAS at 44 points is the pick. It tops both tables: 43 in Words With Friends as well.

The full 8 letters are used by ZYZZYVAS, BEZAZZES and JAZZLIKE.

If you need a narrower cut, the pages linked below split this set by letter and by length.

buzzword: stock phrases that have become nonsense through endless repetition
embezzle: appropriate (as property entrusted to one's care) fraudulently to one's own use
bedazzle: to cause someone to lose clear vision, especially from intense light
blizzard: a series of unexpected and unpleasant occurrences
puzzling: lacking clarity of meaning

How many 8-letter words are there?: 28,420 in the Tournament dictionary, which is the public-domain ENABLE word list. The Broad dictionary adds more.
What is the highest-scoring 8-letter word?: ZYZZYVAS at 44 points, counting tile values with no board multipliers.
Are all of them listed here?: No. The page shows the 300 highest-scoring; the pages linked below break the full list down by starting and ending letters.