Editions of the Paston Letters
The medieval letters and documents were first published by John Fenn across some 5 volumes, beginning in 1789.
Since Fenn, there have been three key scholarly editions of the medieval letters.
The first was at the close of the 19th century by James Gardiner. In this edition, the material is presented in chronological order, along with miscellaneous items about life and times in 15th century England. Gairdner has made many corrections and additions to the medieval letters. He published a new edition in 1904 with further letters and comments, and used a different numbering system. There was a direct reprint of his work in 1910 but this used the first edition; the source used for the letters on thiis site is the 1904 edition.
Then in the 1970s, Norman Davis published two volumes, where he arranged the correspondence en bloc. The intention was to showcase the collections of each of the 15 family members. The effect is to make individual Pastons to stand out more clearly. Arguably though, the collective family tale is harder to follow.
Most recently, Beadle and Richmond have completed the third volume of Davis's enterprise, which includes new records and documents (among other material, there is a significant addition to Fastolff related documents in this volume).
There is also an easily accessible modern English translation: The Paston Letters: A Selection in Modern Spelling Ed. Davies, Oxford World's Classics, 1999.
There are other valuable books to help us understand the letters. Helen Castor's 'Blood and Roses' brings the Pastons to life by using the letters to tell the Paston story. It's an excellent starting place for getting to know the medieval Pastons.
Colin Richmond's series of books, starting with 'The Paston Family in the fifteenth century: The first phase'. takes a more academic approach in analysing dates, locations and events in the letters. It will all depend on how deep you want to delve into family life in the 15th century!