Still wondering how I missed all your posts. Apologies. Though I guess some queries were answered. Still answering for the sake of it...
Sir 50 f1.8G is a great lens. Ultra sharp and fast. They rightly call it the nifty fifty. You cant go wrong with it. I would recommend a telephoto like Nikkor 18-105. People swear by 3rd party lenses but still as per my own personal inclination I would stick to proprietary lenses. Have heard good review about 18-200 of Sigma. Not sure if 3rd party lenses are that sharp at 300 end.
Best for a newbie is Auto with flash off otherwise put in A mode, dial in the aperture at 1.8, put ISO at Auto, keep pop-up flash down and use the 50mm and fire away. This is for night. For daylight you can move between 3.5 or whatever the highest is on the 18-300 Sigma and shoot with ease in any setting. Personally I use the A mode most of the times. Easy to adjust and simple to handle. ISO is manual although.
Apologies once again brother