The Nikkor 105mm is an excellent macro lens and a good choice for general purpose.
There are both longer and shorter focal length macro lenses. The longer ones give you more working distance, but also shallow Depth of Field and are harder to hold steady. The shorter can give too little working distance for a lot of subjects.
Besides the 105mm Nikkor, around that focal length there are also Tamron 90mm (two versions), Tokina 100mm and Sigma 105mm macro lenses, all of which are pretty darned good, too.
As to flash, there are two types of specialized flash for macro purposes: dual flash or "twin lights" and ring lights.
Below are Canon examples, because that's what I shoot... but the same things or very similar are available for Nikon.
This is a Canon MR-14EX Ringlite on my MP-E 65mm macro lens:
The MP-E 65mm is an extra high magnification macro lens, no less than 1:1 and up to 5:1 (5X life size) magnification. It's pretty much the only lens I use the Ringlite with... I just don't care for the lighting effects that ring lights give on less than roughly 2:1 magnification. At less than that, ring light flash tend to make for a rather flat lighting, not a lot of shadows. That might be great for scientific, medical and forensic shots... But not great for anything where I'd like to have some nice modeling effect, with some shadows and highlights. The below image of a tiny, newly hatched snail was shot with the above rig, at about 3X life size and with the ring light flash set for maximum modeling effect, 8:1 lighting ratio between its left and right flash tubes.
For lower magnification shots, such as the 1:1 that's the maximum magnification possible with the Nikkor 105mm Micro lens and most macro lenses (unless additional accessories are used), I prefer to use a dual macro flash that gives a lot more control over flash head positioning and greater effective differences in shadow and highlights. This is the Canon MT-24EX Twinlite that I use...
The Twinlite is shown above with its two heads mounted on a Lepp/Stroboframe dual flash bracket, which allows a lot more flexibility positioning the heads than the standard mounting ring Canon provides, that clips onto the front of the lens. Here's the bracket itself (no longer made, but there are similar avail. from other manufacturers):
Both types of macro flashes are relatively low power, designed to be used close up without completely over-powering the subject with too strong light. They have limited use for anything other than macro purposes.
But, I sometimes don't have those specialized flashes with me and have found that a single, standard flash can also be used quite effectively. I nearly always have a standard flash handy. For close-up work with it, the trick is to diffuse it in some way to reduce the output and to be able to aim it toward the subject. Here is one of my Canon 580EX II flash attached to the camera with an off-camera-shoe-cord and with several layers of white gauze bandage over the head, held in place with a rubber band:
That gauze bandage over the head nicely holds back the flash output, at the same time it diffuses it for a more even effect. There are brackets available to mount the flash, with tilt to be able to aim it at close-up subjects. But I usually just hand hold it because that's quick and allows me maximum flexibility where I position the flash. All three of the macro shots below were done with a single flash used in this manner:
The two shots of the praying mantis are "full flash" used to make the background go completely dark (it was a distracting tangle of grass and branches). The closer of those mantis shots uses the flash held well off to the left hand side, to create stronger highlight and shadow effects. The second mantis shot was done with the flash more directly on, closer to the lens axis, for a lot less shadow modeling effects. The shot of the spider is "fill flash" with a strongly backlit subject, positioned rather directly. In all three shots, I just handheld the flash.
If the gauze bandage trick is too low tech and too "MacGuyvered" for you, there are diffusion accessories and mini softboxes available for use with many flashes that can serve the same purpose (I just like something that costs almost nothing, weighs very little and takes up minimal space in my camera bag... plus might be nice to have on hand if I ever get injured!
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Again, all the above are Canon examples and those flashes I'm using won't work properly with Nikon. But, I know similar are available for and possible with Nikon... both OEM products from Nikon themselves and other products from third party manufacturers.
Something else you might want to consider are continuous LED light sources. These are relatively new and are available in relatively small sizes that would be appropriate for macro work. Continuous lighting can be easier to use because what you see is literally what you get... Rather than the very fast burst from a flash, they give continuous light output. In the past, continuous lighting was done with "hot lights", that literally got hot and weren't usable for a lot of things. But LED are "cool lights", so don't have that problem. Might be worth looking into and could probably serve for video work, too, if you'll be doing any of that.