55-300 is a telephoto zoom, not the most versartile lens for shooting indoors as it's relatively slow (doesn't let in much light). It's fine for outdoors/nature though. I would recommend getting something wider, especially if this is your only lens. 55mm on the d7000 is around a portraiture focal length, meaning it's usually used for close ups of people. If you attempt to shoot groups of people you'll find yourself backing off a long way to get everyone in!

Unfortunately shooting parties and telephotos don't mix very well due to the combination of low light, small aperture, camera shake and limited flash range. I would definitely recommend you getting a 50 f/1.8 lens as well as / instead of the kit lens. The 50mm will let in about 8x as much light as the 55-300 or the kit lens (it's about three stops faster). This comes in very handy shooting at parties.

However the 50mm isn't the most flexible lens, it suffers the same problems as the 55-300 in that it's not wide enough for many uses. I would still get one if I were you, but pair it with a standard length zoom. I'm not that familiar with the Nikon range but I'm sure someone here could suggest a few options.