The two longest available words are:
1- Question = y,t,a,m,r,h,e. 2- answer = my heart❣️
my heart
my heart
France.
The letters 'ustoodwernj' = justone word.
Fossil
my earth
Those letters spell the romantic term "my heart" (and the not so romantic term "the army").
There are 4 distinguishable letters in the word fish, so there is 4! or 24 different ways can you arrange the letters in the word fish.
The only words you can make with these letters are: ESTERIFY OUTFIRES REEFIEST
Tubelight
There is no single English word that meets the criteria.