The Princess Tales book series was released as a single compendium in 2014.
Now, for the first time, the six beloved Princess Tales are together
in one magnificent volume:
The high jinks begin in The Fairy's Mistake, which pokes fun at a
meddlesome fairy whose plans for good go terribly awry. In The
Princess Test, the author spoofs the notion that a pea can prove a
person's pedigree. Princess Sonora and the Long Sleep features a
genius of a princess, a hundred years of snooze, two princes, and a
flock of balding sheep! Cinderella is a boy in Cinderellis and the
Glass Hill, and the glass slipper is a glass hill. In For Biddle's
Sake, Parsley tries to forget her beloved prince and get used to life
as a Biddlebum Toad. The road to happily-ever-after isn't easy when a
baker's son and a princess fall in love in The Fairy's Return.
The other series you've mentioned are broadly independent of each other and should simply be read in their published orders.
For the record, the novel "Fairest" is set in the same fictional universe as "Ellan Enchanted". Per wikipedia
Fairest is a 2006 novel by Gail Carson Levine. It uses some plot
elements of the classic Snow White and set in the same world as Ella
Enchanted. The kingdom of Ayortha, the setting of the story, is the
neighboring kingdom of Kyrria, where Ella Enchanted was set and the
story makes several allusions to the previous work.