I don't want to sound stupid, but how do i get the dust off of the sensor?, also, could it be oil?, I have heard a few horror stories about Nikon's getting oil on the sensor.
Not a stupid question at all. The first thing to do would be use the built-in cleaning function: Setup menu (Wrench icon) and scroll down to the "Clean image sensor" option. Press OK and follow the directions. If that doesn't do the trick I'd suggest having a professional camera shop clean your sensor for you. If you don't have a shop that will wet clean your sensor, you can do it yourself with a kit. Just google DSLR sensor cleaning kit; I'm sure you'll find lots of kits and Youtube videos that will show you how to do it. I have my sensor cleaned professionally by a local shop once a year whether I think it needs it or not. I really should learn to do it myself...
The possibility of it being oil is very slim. The issue you heard of plagued the D600, so you can relax, dust on the sensor is one of those things that all digital photographers learn to deal with.
The camera was on auto when i took the pic. of the yard stick. but the numbers are,,, 105mm lens, ss 1/60, f5.6, iso 500
Personally, I don't think you really need to fine tune your autofocus... You can if you want but I think the real issue here is one of technique. When shooting with zooms, or telephoto lenses, you need to keep the shutter speed *at least* equal to the focal length you are shooting at. This means if you're shooting at 200mm, your shutter speed needs to be 1/200 second, or faster (1/320 would be a minimum in MY book), in order to ensure sharp focus.
The reason for this is that the magnification of a tele/zoom is a double-edged sword: It magnifies the image but it also magnifies the slightest tremor of camera shake or vibration. Even the motion of the shutter itself can blur your photo when using the big zooms. In your example above you shot at 105mm and 1/60 second. Good technique would dictate a shutter speed of, say, 1/125 at the focal length. I can hear you complaining already that you can't shoot at that speed without opening your aperture and what that will do to your depth of field and so on and so forth... And you're right. It's also partly what makes photography two things: 1. Difficult at times and 2. An art form. Your best option, typically, is to increase your ISO. Of course that brings its own set of issues but that's just photography for you.
Photography is a ceaseless juggling act of Aperture, Shutter Speed and ISO... Always, always, always.
Bonus Edit:
7 Tips for Getting Razor Sharp Focus
.....