Vertical alignment of fonts from different language groups

Dear Fellow TeX enthusiasts,

Thanks very much for help with solving earlier problems with the Devanagari Package. I'm working without KOMA-Scripts for the moment in Xelatex/Xetex and am trying to align Devanagari, the (Standard) Roman Font Family, Cyrillic and the Tibetan script so that

(a) they are vertically aligned on the "head"-line of the font (rather than on the baseline) --- it seems that The cyrillic (Linux Libertine) is automatically aligned with the standard Roman setting of the TeX. If necessary, I would make the Tibetan and Devanagari fonts a wee bit smaller, but don't quite know how (e.g. scaling=0.8?)

(b) spacing between lines is not affected by the use of different writing systems/Font - if anybody knows how to align this one, too, I would be really grateful :-) different scripts.

(c) Font for the main text in Sanskrit should be Sanskrit 2003, and the Font for Sanskrit in the Footnotes should be the AA Nagari Shree Font (also aligned with Roman and Tibetan and Russian). Would you maybe know how I do this?

Minimal working example follows:

\documentclass[12pt,a4paper]{report}
\usepackage{polyglossia} %

\usepackage[hyphens]{url}

\setmainlanguage{english}
\setotherlanguages{hindi,tibetan,russian}
\newfontfamily\devanagarifont[Script=Devanagari,Mapping=velthuis]{Sanskrit 2003}
\newfontfamily\tibetanfont[Script=Tibetan,Mapping=wylie]{DDC Uchen}
\newfontfamily\russianfont[Script=Cyrillic]{Linux Libertine}

\PolyglossiaSetup{tibetan}{
script=Tibetan,
scripttag=tibt,
hyphennames={nohyphenation},
fontsetup=true
%TODO localalph={xxx@alph,xxx@Alph}
%TODO localdigits=tibetannumber
}

\begin{document}
How can we integrate the alignment and sizes of the roman, sanskrit and Tibetan characters?\begin{hindi}{d.r.s.tvaa si.mha.m karmaphalam\footnote{.r.siswaami.h}}  \end{hindi} {\begin{tibetan}{bde.ba.can.zhes.bya.ba'i.zhing.khams.'dir|\footnote{smon.lam.'di.gi.mdzad.pa.po.su.red} \end{tibetan} and Roman letters in comparison finally test Russian \begin{russian}{вот это тест посмотрим как это в конце концев будет} \end{russian}
\end{document}


Scale=MatchUppercase

\newfontfamily\tibetanfont[Script=Tibetan,Scale=MatchUppercase]{Kailasa}