The mode dial on my 3-month old D7000 is tight enough - no more loose than the one on my D90. The dial on the D90 sometimes accidentally shifted when I put the camera in its bag or when taking it out. I quickly got into the habit of checking the dial position everytime before starting to shoot. Following the same habit with the D7000 means it's not an issue for me.
The D7000 has an autofocus fine tuning adjustment in the menus. If you suspect it's back-focusing then print a focus chart and test the camera's autofocus. If it's off you can try to fine-tune the autofocus till it's right. Mine was so far out that I had to get the camera back to Nikon to fix the back-focus. After I got the camera back I fine-tuned the autofocus on each of my lenses again, and I was pleasantly surprised at how well it focuses now. During a recent holiday I got some really sharp pictures. I know now that if my picture comes out soft it's poor technique on my part rather than faulty camera focus.
I have also found the white balance on the D7000 to be generally more accurate than that on my D90. Having said that, white balance doesn't bother me on either camera because I shoot in RAW and always fine tune white balance in Photoshop anyway.
There were some initial complaints of blown highlights in high-contrast scenes with early model D7000's, but I have not seen this problem on my D7000. It was an issue on my wife's D40, but then I set the camera to a lower default contrast for jpeg shots, and it's not a problem now (my wife shoots only jpeg). If the camera is set to produce higher contrast jpeg pictures you'll be more likely to blow highlights than with lower contrast settings. You can always increase contrast during post-processing. Also check the D7000 operator's manual. The metering can be fine tuned to reduce the likelyhood of blowing highlights or overexposing.