Yes but only with manual focus.
Yes in non i-ttl auto and manual
i bought one....doesn't appear compatible
Yes, it will fit. However, you will still need to see if the lens you have has or does not have features like autofocus or CPU connectors that will carry all the info that your camera needs... If it is a Nikon Lens it will work fine. So will others like Sigma, Tamron and Tokina. Carl Zeiss may not give you all the functions but will work in manual mode.
Yes. The Nikon D40x has a hot shoe on top of the built-in pop-up flash. Be sure to check the compatibility of any external flash unit that you attach to the camera. Note: The question was changed after the first answer was posted, so that the two do not match now. An approach to the new question is that a Nikon D40x is an entry level DSLR, and you may want a flash in that price range. Suitable units are marketed by Nikon, of course, and by Sigma, Sunpack, Vivitar, and Quantary. Features vary with specific models, so you will want to investigate the features-per-dollar for the various units. [spelvin]
A Nikon EM has a standard Nikon mount, so you can use any lens that'll fit on a Nikon, except for a Nikon Series G lens, on an EM. A Series G will fit but it won't work because there's no aperture ring.
It works but no auto focus just manual focus.
Yes. Any lens that works with a D60 will work the same or better on a D7000.
Depending on what type of lens they are. They probably are AF lenses, so it'll work, but without the autofocus function. That means you'll have to make the focus manually.
Most Nikon lens will work in complete manual mode, but to get the most from the lens (auto-focus, metering) stick to Nikkor lenses with AF or G in the title. Full comparability chart in the related links below.
ED has nothing to do with the camera mount; it is a lens (glass) quality so yes, it will fit
yes it does. I just bought one off of eBay and its not a lens its a lens attachment but it works well and im pleased with it.
Yes. Make sure you purchase your sigma lens with the F-bayonet. Here is their lens finder: see related link