Can i buy the camera body by itself and purchase this lens?
Can i buy the Nikon D5100 16.2MP Digital SLR Camera Body
7 separately buy this lens?
Nikon AF-S DX NIKKOR 55-300mm f/4.5-5.6 G ED VR Lens. Like is it compatible? Or do i need something else to fit it on
No worries, the AF-S 55-300 mm is fully compatible with the D5100. Nothing else is needed, but something like a UV filter to protect the front lens would be advisable.
D5100 is a good camera. And the lens you have mentioned is a must have thing for outdoor and travelling shooting.
The deal that includes the 'standard' zoom (18 to 55mm) usually means that it would be silly to not buy the deal, probably the 'body only' is only a few dollars/pounds less than the combined deal. You would be buying a medium tele zoom (55 to 300) with no possiblity of standard or wide angle if you ignored the 18 to 55. But it's your choice, some shop will doubtless make a deal. Only the more expensive bodies usually are sold as 'body only'.
It is completely compatible, but the 18-55mm range is where most photographers do 80% of their shooting. It would be kind of stupid not to get that lens. Get the kit and the 55-300
It is possible to buy a D5100 body only. The 55-300mm is a pretty good, although not great lens. However, you would not want it as your only lens, because in the majority of situations you would want a wider angle. The 18-55mm kit lens is a good one, and less expensive if bought as part of a kit. Many people prefer to get the body a la carte and get the 18-105mm, which is reputed to be as sharp as the 18-55mm while being more versatile.
The 55-200mm is lighter and less expensive than the 55-300.It of course lacks the 200-300 range. The 55-200 is reputed to be a little bit sharper, although not by much. In the 200-300 range the 55-300 has pretty good center sharpness, but it can get noticeably softer in the corners. The 70-300mm VR (the good one, not the cheap one) is reputed to have better corner sharpness than the 55-300mm at 300mm, and it focuses faster and with less struggling in low light. It is more expensive, bulkier, and heavier. So the 55-300mm has some pros and cons in its category.