You didn't mention what version of Lazarus you are using, nor on what platform, so I presume you are on Windows, with latest version.
On Windows you need to copy the files on the folder where the SynEdit package is (the package that is compiled with the IDE), and recompile the package, so the IDE version of the package gets the wordwrapping functionality.
Copying to your project folder is not enough, as you are still using the original version of the files that comes with the package.
Once you recompile the package, you should have the oeWordWrap property, and be able to Save/Load from Stream.
As an example, I created a Frame with a TSynEdit on it, on the constructor of the frame the highlighter is created and assigned to the SynEdit (a custom highlighter in this case), Memo1 is the TSynEdit:
FHL := TSynMINGGASyn.Create(Memo1);
[..]
FHL.KeyWords.Add('#SS');
Memo1.Highlighter := FHL;
Memo1.Options2 := Memo1.Options2 + [eoWordWrap];
Later..
st := Tarea.CreateBlobStream(Tarea.FieldByName('contenido'),bmWrite);
try
Memo1.SaveToStream(st);
finally
st.Free;
end;
Hope this helps.
David.