@Nero
You'll need a transmitter (trigger) to be able to efficiently use your flash off camera. There are some ways around this if your camera has a built in flash, but I'd still recommend the transmitter allowing you to make adjustments to the flash or strobe directly from the trigger. They're brand specific, so be sure to get one for Nikon. I have the R2 Pro N, like
THIS one, but you might want to look into the R2 Pro Mark II N. It changes the hot shoe attachment from screw in to lock in. My transmitter has never come off unintentionally, but the extra reassurance with a lock would be nice. Other than that, the round head flash accessory kit is pretty handy, allowing use of quick and easy modifiers and diffusers. Once you get the Ad200, be sure to get the round head with it and then
THIS accessory kit works great with it as well as with the V1. Stands are pretty self explanatory- find one that's tall enough for your needs. The taller they are, the heavier they are. 9 feet is probably plenty tall, keep in mind how you'll light your subject though. If sticking to 45 degrees off center and 45 degrees above, your light has to be taller than your subject. You could get an umbrella but getting a Bowens mount adapter like
THIS allows a lot more options for softboxes. Just be sure to get the S2 which allows the round head to sit in the clamp inside the adapter. If you don't want to or can't bounce the light off a wall or ceiling, you could get a softbox like
THIS one that just slips over the bowens mount ring or
THIS one that clicks into the bowens mount ring. Or skip the bowens mount ring and stick with an umbrella. Lots of options, hope this small list helps.