If you were a very fast guy NYAC, WSX, CPTC and until recently Urban Athletics were the best teams (in that order). They're sponsored to various degrees. At 1:28 (very solid club pace), I'd focus more on where you live. In North Brooklyn there's NBR which is huge, very very friendly and organized and probably the 4th / 5th fastest team in the city. In Queens there's QDR, In South Brooklyn there's South Brooklyn Runners, near Orchard Street there's Orchard Street Runners, near Warren Street there's Warren Street Runners - you get the idea. It's an incredible running scene.
Best areas to run are Central Park, Prospect Park and then any of the waterfronts. The West Side is the best known but it's very popular. The East Side is also great and you can *almost* do a loop now from the very top of Manhattan in Inwood, down the West Side and back up the East to 12Xth street without crossing traffic. I do most of my running around the Brooklyn and Queens waterfront - you can run from Astoria to Red Hook without any hassle and further South under the Verrazano is beautiful. Once you get the hang of running in the streets the whole city is runnable - central Manhattan's too busy but everywhere else is easy to explore. Roosevelt Island, Randall's Island, the Manhattan, Williamsburg, Tri-Borough and new Bronx bridges...
Winter sucks. They plow very efficiently but the ice and slush will get you down. Summer also sucks and is oppressively hot. There are basically about 4 good weeks of running weather a year.