Eh, ymmv w/booze. I tend to just get a headache, and most alcohol doesn't taste that good to me, so it's a lose-lose for me unless it happens to be a drink I like. Watching other people be drunk can be entertaining, however!

Best karaoke song - it depends! Don't Stop Believing is definitely popular, as well as anything by Queen - the only problem with them is they kind of require actual vocal chops to sing! You can always tell when the end of the song is coming in Don't Stop Believing, because everybody's out of breath for the big notes by then. Wannabe pretty much only requires that you talk fast.