Sorting of bibliography and index

Question

In the following MWE, I want the bibliography to be sorted by the last name, first name of the first author/editor, and first name, last name of subsequent authors. In the attached image, they are sorted by lastname, first name for all authors, editors, even though subsequent authors are listed as first name last name.

In the index, I want {\"U} to be sorted as U, and not as a separate group.

\documentclass{memoir}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}

\usepackage[citestyle=authoryear-comp,bibstyle=authoryear,hyperref=true,maxcitenames=3,doi=false,url=true,backend=biber,natbib=true,maxbibnames=99,uniquename=false,uniquelist=false,indexing=cite]{biblatex}

\usepackage[xindy]{imakeidx}
\newcommand*\lettergroup[1]{}

\makeindex
\usepackage[itemlayout=abshang,indentunit=10pt]{idxlayout}

\usepackage{filecontents}
\begin{filecontents*}{\jobname.bib}

@article{usami2012some,
  Author =       {Usami, Y and Rana, Thomas},
  Journal =      {Review of Alpha Studies},
  Number =       2,
  Pages =        {74--105},
  Title =        {Some aspects of guarantee},
  Volume =       2,
  Year =         2012
}


@book{benoist2003,
  Editor =       {De Benoist, Bruno and Maria Andersson and Ines Egli
                  and Bahi Takkouche and Henrietta Allen},
  Publisher =    {World Health Organization},
  Location =     {Geneva},
  Title =        {Iodine status worldwide: {WHO} global database on
                  iodine deficiency},
  Url =
                  {whqlibdoc.who.int/publications/2004/9241592001.pdf?ua=1},
  Year =         2004,
  Bdsk-Url-1 =
                  {whqlibdoc.who.int/publications/2004/9241592001.pdf?ua=1}
}

@book{benoist2008,
  Editor =       {De Benoist, Bruno and Erin McLean and Ines Egli and
                  Mary Cogswell},
  Publisher =    {World Health Organization},
  Location =     {Geneva},
  Title =        {Worldwide prevalence of anaemia, 1993--2005: WHO
                  global database on anaemia},
  Url =
                  {whqlibdoc.who.int/publications/2008/9789241596657_eng.pdf},
  Year =         2008,
  Bdsk-Url-1 =
                  {whqlibdoc.who.int/publications/2008/9789241596657_eng.pdf}
}


@article{morris2008effective,
  Author =       {Morris, Saul S. and Cogill, Bruce and Uauy, Ricardo},
  Journal =      {The Lancet},
  Number =       9612,
  Pages =        {608--21},
  Title =        {Effective international action against
                  undernutrition: Why has it proven so difficult and
                  what can be done to accelerate progress?},
  Volume =       371,
  Year =         2008
}

@article{biberanak2002,
  Author =       {Biber, F. Z{\"u}mr{\"u}t and {\"U}nak, Perihan and
                  Yurt, Fatma},
  sortname =    {Biber, F. Zumrut and Unak, Perihan and Yurt, Fatma},
  Doi =          {10.1080/10256010208033316},
  Journal =      {Isotopes in Environmental and Health Studies},
  Number =       2,
  Pages =        {87--93},
  Title =        {Stability of iodine content in iodized salt},
  Volume =       38,
  Year =         2002,
  Bdsk-Url-1 =   {dx.doi.org/10.1080/10256010208033316}
}

@article{wang2014trends,
  Author =       {Wang, Dong D. and Leung, Cindy W. and Li, Yanping and
                  Ding, Eric L. and Chiuve, Stephanie E. and Hu, Frank B.
                  and Willett, Walter C.},
  Journal =      {JAMA Internal Medicine},
  Number =       10,
  Pages =        {1587--95},
  Timestamp =    {2015.02.27},
  Title =        {Trends in dietary quality among adults in the
                  {U}nited {S}tates: 1999 through 2010},
  Volume =       174,
  Year =         2014
}



\end{filecontents*}
\addbibresource{\jobname.bib}

\begin{document}
\parencite{wang2014trends,morris2008effective,biberanak2002,usami2012some,benoist2003,benoist2008}

\printbibliography

\printindex

\end{document}

I compile this using:

xelatex -interaction nonstopmode mwebib biber mwebib xelatex -interaction nonstopmode mwebib xindy -M texindy -M page-ranges -L Turkish -C utf8 mwebib.idx xelatex -interaction nonstopmode mwebib xelatex -interaction nonstopmode mwebib