Very interesting.
the French don't shout "encore" to request a repeat performance - they shout "bis", which is Greek.
Sorry, but bis is good Latin for 'twice'; cognate with Greek dis, Sanskrit dvis from PIE *dwis.
"Contra" itself is mystifyingly described by the OED as "abl. fem. of a compar from com, cum with", but it looks like it's from "cum" + [some 1st declension noun?].
Prepositions, and other particles, are strange bits of words. The idea of a comparative of a preposition may seem strange, but English has nigh, near, and next and others.
The 't' in against is epenthetic; the form in Middle English was againes. Again from on + gean 'still, again' (cf. German gegen).
