1.Can you provide an English translation of the German lullaby
"Schlafe, mein Prinzchen, schlaf ein "-music by B.Fliess; words by
F.W.Gotter? If not,could you supply the German words?

2.Can you tell me where I can get biographicalo notes on Fliess and
Gotter?

Hello.

The REC Music Foundation offers the German and English words
(translation by Emily Ezust) for "Schlafe, mein Prinzchen, schlaf ein"
on its web site:
http://www.recmusic.org/lieder/g/gotter/wl.html

According to Tim's Classical Music Database,a web page from the
Netherlands, Bernhard Flies was born circa 1770 in Berlin:
http://www.timdebrie.myweb.nl/f/FliesBernhard.html

Flies' year of birth is also listed as 1770 on Yahoo Music's classical
music page:
http://shopping.yahoo.com/shop?d=cmp&id=fliesbernhard

The 1911 Encyclopedia offers a one-paragraph biography of Gotter.  The
biography appears in the middle of the following web page, beginning
with "GOTTER, FRIEDRICH WILHELM (1746-1797), German poet and
dramatist, was born on the 3rd of September 1746, at Gotha."
http://34.1911encyclopedia.org/G/GO/GOTTFRIED_VON_STRASSBURG.htm

search strategy: schlafe mein prinzchen, sleep my little prince,
gotter, flies

I hope this helps. Good luck with your research.