How to typeset Cyrillic characters with the XeLaTeX engine?

Question

The Cyrillic characters in pdf are not appear if using the XeLaTeX (from Why does \usepackage[T2A]{fontenc} take over?):

\documentclass{article}
\usepackage[T2A,T1]{fontenc}
\usepackage[utf8]{inputenc}

\usepackage[russian,english]{babel}

\renewcommand{\familydefault}{\sfdefault}


\begin{document}

\renewcommand{\sfdefault}{PTSans-TLF}\normalfont
\section{PTSans}

Todd is a cat. \textcyrillic{у меня есть машина. я очень харашо.}


\renewcommand{\sfdefault}{fds}\normalfont
\section{Droid}

Todd is a cat. \textcyrillic{у меня есть машина. я очень харашо.}


\renewcommand{\sfdefault}{fco}\normalfont
\section{Comforta}

Todd is a cat. \textcyrillic{у меня есть машина. я очень харашо.}


\renewcommand{\sfdefault}{fca}\normalfont
\section{Cantarell}

Todd is a cat. \textcyrillic{у меня есть машина. я очень харашо.}


\renewcommand{\sfdefault}{iwona}\normalfont
\section{Iwona}

Todd is a cat. \textcyrillic{у меня есть машина. я очень харашо.}


\renewcommand{\sfdefault}{fos}\normalfont
\section{OpenSans}

Todd is a cat. \textcyrillic{у меня есть машина. я очень харашо.}

\end{document}

-------EDIT--------

I need to get these aims:

1. XeLaTeX engine
2. use the condensed iwona fonts in mathematics environment
3. use the condensed iwona fonts for main text (including both Latin and Cyrillic letters)
4. use the txtt fonts typesetting URL
5. use the txtt fonts instead default ttfamily

Here is my code:

\documentclass{article}

\usepackage[utf8]{inputenc}
\usepackage[no-math]{fontspec}
\renewcommand*\ttdefault{txtt}

\usepackage[T1]{fontenc}
\usepackage[condensed,math]{iwona}

\usepackage[russian,english]{babel}

\usepackage{url}

\begin{document}
\url{http://google.com}\\
\texttt{TXTT-FONTS}\\
\textcyrillic{Ломоно́сов}\\
$\sin^2 x+1$\\
today\\
\end{document}

Maybe I'm missing something, so I'd be happy to be pushed in the right direction.

Answer 1

The txtt font is not suitable for usage with fontspec; also, inputenc should not be used and you have to select a main font with support for Cyrillic, as the default Latin Modern fonts haven't it.

The iwona package should be loaded before fontspec and fontenc is useless in this context. Then you need to choose Iwona with fontspec commands.

\documentclass{article}

\usepackage[condensed,math]{iwona}
\usepackage[no-math]{fontspec}
\setmainfont[Ligatures=TeX]{Iwona Cond}
\setmonofont{CMU Typewriter Text}

\usepackage[russian,english]{babel}

\usepackage{url}

\begin{document}
\url{http://google.com}  

\textcyrillic{Ломоно́сов}  

$\sin^2 x+1$  

today
\end{document}