Casino prices...can't help you, we don't gamble at all - sorry.
Drinks...they are average, we drank long island iced teas and they were $4 a pop, small, not bad. Frozen drinks are more. It depends which cruise line you go on too! When we sailed princess they measured each drink with shot glasses but on Carnival Imagination they free pour so you get more bang for the buck.
We always take extra because we'll put rum floaters on top to make the drinks last longer. It adds up when your drinking all day and night. We didn't even drink that much and our bill the first time was 250 and the next 370 (but we bought stuff at the ship store). Two guys that were at our table drank beer then entire time and racked up a $700 bill...they were pretty much drunk the entire time.
It all depends on how much you drink...we got those plastic sqeeze bottles that have coolers around them with a strap to hang on our arm...we go buy a rum runner and put a floater on it when we get to our seat!
Drinks...don't know what your poison is, but here are a few prices I jotted down from my August cruise. Wine by the glass $5.75, Martini $5.18, Margarita $4.54, Domestic Beer $3.74 or you can get the daily "special" drink in the non-souvineer glass for $3.39 all these prices include the automatic 15% tip that is added to the cost.
Casino...don't play the tables so can't answer that one, but a wide variety of slots from .05 cents to dollars...I WON $400 on a quarter machine and $80 on a .05 cent slot...so my small investment paid off for me!!!
If your a drinker watch because your Sail & Sign will start adding up pretty quickly!!!
Recently on Carnival, I found that drink prices varied even between bartenders for the same drink. Expect to pay $4-6 depending on what you drink. I usually bring my own liquor b/c the cost is average but the drinks are weak (I'm a bartender). I bring a flask for floaters on the drinks I do buy. Casinos usually comp drinks if you are gambling but not on cruise ships (at least my experience).
On gambling: there are a wide variety of games to play. Most card games will have a minimum bet of $5, $10 or $25. I always play the $5 or $10 blackjack and I walked away with $300 on my last cruise. Just know when to call it quits.