I think you are going to be out of luck with the Wicked tickets.
They are pretty much sold out solid through the beginning of the summer and then some. I know a new block of tickets for November performances was just released early this week.
Even if you did stumble upon some, getting three (or more) tickets to one performance will be extremely tough. (Sorry, I know this isn't what you were hoping to hear.)
Some are sold on ebay. You'll pay dearly for them, and I would be very very diligent in checking the seller's reputation and number of past transactions (you'll be talking about at least $600 for 3 tix on ebay).
Check out the Wicked website at
www.wickedonbroadway.com I believe they have message boards which may assist you further.
Do yourself a big favor if you do intend to buy tickets......print out a GOOD seating chart from the Gershwin Theatre .... I like this one:
http://www.gershwin-theater.com/nyct...atingplan.html
because this is a modern NY theatre, not like the usual Broadway theatres. The seating area is much wider and you really need to know the exact location you are in (for instance, orchestra seats in row Q side section are actually good, as you can see that there are no rows directly in front of you). Be aware that many of the orchestra seats which are on the wall sides (up to Row L at least) have limited view of the stage.
Others here may have better suggestions as to how you might be able to secure these tix, but seeing that you are looking at a peak holiday week, I think you might want to consider other shows.....and I would definitely get those tickets now.
As for restaurants, well I think half the fun is walking and finding your own, but I did notice this link that might interest you.....good price, a 'name' restaurant.....might be one to consider
http://www.21club.com/web/onyc/onyc_c5a1_offers.jsp
Good luck.