I've also seen the first word spelled Flosst, Floesst, and Flöst or any combination. I'm finding it very hard to locate the lyrics to it.
I know that the first spelling is the correct one, but many people have trouble typing it that way.
It can be heard here:
http://www.imeem.com/classicalmusic2/music/C8mIoXuQ/symphonieorchester_des_bayerischen_rundfunks_orchestra_no/
Phil
Favorite Answer
Flößt, mein Heiland, flößt dein Namen
Auch den allerkleinsten Samen
Jenes strengen Schreckens ein?
Nein, du sagst ja selber nein. (Nein!)
Sollt ich nun das Sterben scheuen?
Nein, dein süßes Wort ist da!
Oder sollt ich mich erfreuen?
Ja, du Heiland sprichst selbst ja. (Ja!)
Regarding the spelling of the first word: ß (Eszett) is an abbreviation for ss. Any time you see ß anywhere, it always can be literally substituted for ss. For example, I've seen Richard Strauss spelled Richard Strauß. It's the exact same thing.
The ö is a different story, though. Replacing ö with oe is an English convention of Anglicizing foreign words. I am guessing you saw that from an English publisher or on an English website. Have you noticed that you never see people in English-speaking countries using foreign letters in official documents? They use the English equivalent, which in this case is oe. Similarly, ue can be substituted for ü, and ae for ä.