This app was mentioned in 2 comments, with an average of 1.00 upvote
If you mean Subway maps, I use this developer's Paris app when I go over and it's been great. I used this one last time I was briefly in NYC and it worked well.
I'm on Android and use this offline app but I'm sure there are lots available for iPhone as well if you search for it.
For free wifi I'd say your best bet is to find a Starbucks, they're pretty much all over Manhattan. Also a lot of the subway stations now have Boingo Hotspots, so you can sometimes find wifi there too.