Great to see an OK TR! This reminds me I haven't flown CSA in about 6 months...Starting to get a bit of a withdrawal syndrome...
I am also very surprised by the amenity kits. MAD is a good three hours from PRG, and doesn't get them (or at least didn't when I last flew CSA from there, in Dec 2007).

The MAN loads do seem worryingly low...did you have any glimpse into the other side of the curtain?

As for pre-departure drinks, they normally only get OJ and some vile Bohemia Sekt or whatever it's called on the tray...But everything else is available on request (I usually have a Mattoni).

As for Avis, it does sound quite dodgy...Write in to Avis proper and complain...The fuel trick is very popular in Southern Spain...Renting a Focus for four days from a local operator at AGP, I paid more for fuel than for the rental! However, the rental+fuel price was cheaper than the rental-only quote offered by Sixt- even after my "special discount" for the Sixt Platinum card!