[Ger-Poland-Volhynia] Surname-Less and usage of "VON' before a surname

[GVLESS at aol.com]

The response from Otto, Reiner and Gary Warner has been most  appreciated.  
It helps one that is not knowledgeable of the German language  to better 
understand the usage of certain letters in one's name.  I can  certainly see how the 
name of LESS as used today in America came about because  of the 
pronunciation by German-speaking immigrants.  Thanks for giving the  details on the umlaut 
as well.  
 
I did ask about the usage of the "von" in front of surnames and wondered if  
anyone can give me a reason for this.  Otto mentions the name of Marlene  
Dietrich as her having the original name of "von Losch"  I also found in my  
research of the Bergstraesser name (the "a" has an umlaut above it) of a family  
using the name even today as "von Bergstraesser" and I now recall even a member  
of my husband's family, husband of his sister, as having the last name of 
"von  Hagel" (though I think they spelled it as one word today - Vonhagel).  Was  
this a title or what?  The vonBergstraesser family lived in the Baltic  areas 
and then in St. Petersburg at the turn of the 19th into 20th century with  
the g-grandfather (of a living relative today) being a Russian Admiral in the  
Czar's Navy.  So - was the "title" then bestowed on he and his family  because 
of this position??
 
Again, thanks for all sharing what they know when one like me posts a query  
on this listserv.  The responses are much appreciated.
 
Sincerely,
Virginia Less