I grew up in Bratislava, Slovakia (with public transport very similar to Prague's) and, yeah, the controllers come in quite often, usually in pairs and lock down the bus until they check everybody. I doubt playing dumb would help, if anything you as a westerner will be considered wealthy enough to pay the fine, it used to be 100x the standard fare or so, but this was long time ago...
And, I'm pretty sure drinking age is 18, at least it used to be 10 years ago, doubt it went down
And, I'm pretty sure drinking age is 18, at least it used to be 10 years ago, doubt it went down