elsarticle.cls and biblatex incompatibility

biber will do such a conversion of the text encoding for you in tool mode via

biber --tool --output_encoding=ascii --output_safechars file.bib

If file.bib is

@Article{Beauville:Chern,
  author =   {Beauville, A.},
  title =    {Variétés Kähleriennes dont la première classe de
                  Chern est nulle},
  journal =  {J.~Differential Geom.},
  year =     1983,
  volume =   18,
  pages =    {755--782},
}

then the converted file looks like

@article{Beauville:Chern,
  author = {Beauville, A.},
  title = {Vari\'{e}t\'{e}s K\"{a}hleriennes dont la premi\`{e}re classe de Chern est nulle},
  journal = {J.~Differential Geom.},
  year = {1983},
  volume = {18},
  pages = {755--782},
}

One can convert a .bib file that contains special characters (e.g. umlauts) to a .bib file with safe chars (i.e. TeX equivalents for those special characters) using bibutils:

bib2xml -i unicode mydb.bib | xml2bib > mydb_bibtex.bib

mydb_bibtex.bib will not throw any encoding errors when compiled with bibtex.

From my recent success of a journal submission to Elsevier, I feel it's easier if you put everything (except the figures) into one single tex file and upload as "manuscript".

To integrate the bibliography into .tex file is actually easy, you just compile your original .tex with the .bib file as you normally do. You will find a .bbl file is generated (along with other compiled files, .pdf, .aux, .log, etc.). Then you comment out the \bibliography{...} line in your .tex file and copy all the contents in the .bbl file right after the line.