I've done sound and stage management . . so I can give you a little . . .
sound - have to be able to set up and run anything from a solo artist to a production show with 18 singers on mics and/or a 9-10 piece orchestra (done both!). Helps to have a good 'ear' and be able to ring out a room and monitors quickly as you don't get a lot of time to turn around acts sometimes. Run sound for special events, cruise staff activities, pool deck, meetings, etc.
lights - need to be able to program quickly - hog2 type boards. Automated lights are everywhere, so you need to be able to program and troubleshoot and repair them. Reponsible also for upkeep of lounge lighting and some other public areas.
lounge tech - usually just the 'not the theater' areas - top 40 band, venue setups, and things the main room guy/girl can't get to
stage staff - set up/break down/backstage and all around cruise division 'go and get this'
video - taking care of the roving satellite signal, video support of live shows and events, taping guest events for resale and rebroadcast.
for all the gigs, you really need to be able to do minor repairs, or at least be good at signal flow.
check out some of my previous posts - pretty sure I have a few links to some great articles on these jobs
I know this thread is several months old, but what the hell.....
Maniac is right about all those things! But, when I ran sound and lights way back in the day (1990-1992), it was also one of the greatest experiences of my entire life! I was 23, straight out of a NYC job as a mobile A/V tech for a cartage company on a Friday and plopped square in St. Thomas on Saturday. I had some of the greatest friends there and regret not keeping in touch with them. Still, I had an absolute blast! It was the beginner's ultimate learning experience of my career and was the basis for my work ethic closing in on twenty years. Hope you got the job!
I also did it. Just do the interview and see what they say. I assume you have some exoperience or they wouldn't have offered it to you.
BTW: since this is Carnival, I am guessing that if they phrase it as Audio/Video tech it may NOT be in one of the main showrooms. It may be in their conference center, a smaller nightclub, or just something else.