It is a variation of Lloyd,e.g. Flood, Floyd, Floyde, Floyed, Loyd Nickname for a person with grey hair or who habitually dressed in grey. From the Welsh word llwyd meaning grey. (Hanks & Hodges, p.330).
Another source said
There is evidence that the surnames Floyd, Flood, Flude, Fludd, Floud and Lloyd all began as Llwyd which has been corrupted through time by phonetic change and transcription error.
In mediaeval times Llwyd in Welsh meant grey or brown or of pale complexion and also holy. In the 16th century as the Welsh and English intermarried, the scribes or clerks of the time had difficulty transcribing the Welsh sound of the double " ll " into English and thus they would use the single " l " or " f " instead, thus giving us the curiously spelt versions of the surnames found today, Lloyd and Floyd and later Llowyde, Floyde, Lloyed, Lloud, Fludd, Floid, Flodd, Flood, Fluwett, Flud, and Flude.
Imagine a Welshman named Llwyd marrying an English maiden in England in the late 16th century. The English minister, not being familiar with Welsh spelling, writes down the sound of the bridegroom's surname that he hears, the double " ll " being interpreted as an " f ", thus Floyd for Llwyd or Lloyd. As time passes, local dialects change the sound of the name from Floyd to Fludd or Flood (in Ireland), and then, as the written word becomes more widely used in the 19th century, the last letter " d " began to be transcribed as an "e", thus finally corrupting the surname to today's Flude.
As for the second part of your enquiry, I will have to leave that to some other helpful person in America. Good luck in your quest.