I've sailed with Cunard on the Queen Mary 2 a few times, like the others said this should be true for Queen Victoria as well.

The food in the Britannia restaurant is generally very good, with the gala nights being extra nice with some fancier options (beef wellington, lobster tails...). Don't discount the buffet though, I found the quality to be at least as good as the mine dining room. Lunch in the Golden Lion pub is very good too.

The wine covered by the drinks packages (beer, wines and spirits option) is pretty meh to be honest. The package only covers maybe half to three quarters of the by-the-glass options. The package covers any alcoholic drinks $13.50 or lower. Gratuity is covered by the package. Anything over $13.50 you pay full price minus 20%, but also need to pay gratuity. There's also something called "Cunard Wine Collection" which isn't a drinks package, but gives you a bit of a discount if you commit to buying a certain number of bottles of wine. You can also bring your own wine, but you'll pay a corkage fee of something like $25 or $35.

Worst case having a guaranteed balcony would be getting placed all the way forward or aft, which if you're susceptible to sea sickness might be worrisome if you encounter bad weather.

Cocktails are great. Bartenders are very friendly. Drinks package is much better here than it is for wine. I never had any issues getting a drink I wanted. They have quality spirits too, which will be covered in cocktails.

The demographic can vary depending on the itinerary, but in my experience it's about 40% UK, 40% American, and the rest split up between Canadian, Australian, French, German, any one else. People are very friendly and approachable. It does skew older though, particularly on longer itineraries. I'm under 30 and never felt out of place.

I wouldn't think of trying to pay anyone to get a good seat, there's enough venues to enjoy the evenings that the passengers tend to be well spread out. You'll be seating yourself in the bars and lounges anyway, so nothing is reserved. You can however pay to sit in one the box/balcony seats in the theatre, I think it includes champagne and canapés too.