We spent 10 days in NYC while my DD was taking a training program with the Rockettes. As far as show tickets go, you can get them for that same evening through TKTS at about 40%-60% off, BUT you have to pay cash, wait in line for them in Times Square, and you won't know what shows are available until that day. It really works better than it sounds, but check out their website.
I found that many of the shows hand out discount coupons in Times Square; you take these directly to the theatre and buy your tix there. We saw "chicago" and "Lion King" this way. Once again there's no guarantee what theatres/shows this will be available for, but it's easy, you can pick the show date/time you wish, and you can pay by credit card.
Restaurants are expensive, but one of the more reasonably priced we found was Becco. It's owned by Lidia Bastianich, who you might know from TV. Check out their website. At dinner, they have a pasta flight which is unlimited servings of 3 or 4 different "pastas of the day), includes bread and bean dip (maybe olives, too) for $22 plus tax. They also have really good food... I had osso bucco and it was about $30, I believe, which is a steal for a nice NYC restaurant. They are more downscale, but DH was glad he was wearing a button down shirt with Dockers and I had on capris with a nice shirt. DD16 wore her dress. You could wear nicer shorts, but we were glad we were a little more dressed up. I think Becco is on 10th and maybe 52nd street? It's west of Times Square. Check their website.
Whole Foods in Columbus Circle has an amazing food court,with many different food bars: salad, cold mixed salads (like potato, etc), hot foods, asian, indian, picnic, sushi... a whole bunch of stuff, with a sit-down area or take out across the street to Central Park. Much more affordable than a restaurant, with really good, "real food".