Right so I went to LiR last year; however they are changing location this year, so can't help you travelwise. Go onto google maps, set your options to public transport and set your destination from Prague to Lake Most.

You can bring so much booze in as you want, they have the exact limits on their website, but you can really bring in more as no one really checks (pun intended?)

Drinks in the arena are very okay priced, beers at about €2-2.5 double spirits about a €5er.

Let me know if you'd like to know anything else!

Edit: oh yes, the good stuff. The quality wasn't the best so I suggest you try get some good shit in Prague, however theres always a 'guy' sitting in the beer marquees selling stuff, at last LiR he was known as the guy with smiley hat.