Will the Vivitar SI 70-210 mount on my Nikon D90. Will the AF work properly? Thanks

What is the exact problem? Is the device not working properly? Did you try to charge it, exchange the battery, test it on a different device? Give us more info.

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Vivitar Series 1 lenses were available with a variety of lens mounts for different camera makes. If the lens has a Nikon mount then it will work on a Nikon D80. If it has some other mount then it will not fit.

The TTL contacts on the Nikon are different to the Vivitar.
You can put a remote flash trigger in the Vivitar and use the Nikon's built-in flash to trigger the Vivitar flash using the remote flash trigger.

Make sure you set the aperture ring on the lens to its smallest setting (largest f/number) and lock it. Without doing so, the lens will not communicate properly with the camera and thus you will not get the autofocusing.

In a word, no. If the Quantaray lens fits on the Minolta, then it has a Minolta mount. A lens requires a Nikon mount to fit on a Nikon D90. The two mounts are not interchangeable.

Now, if it was an ancient Quataray manual-focus lens with a T-mount adapter, then all you would need is a Nikon T-mount adapter to replace the Minolta T-mount adapter...

Check to see whether you're set for AF-C in M, A, and P modes. The AF assist doesn't light in AF-C. Auto mode automatically selects AF-S, so the AF assist would come on then.

Hello,
The Nikon D90 works well with the Nikon AF 50mm lenses and most other brand Nikon fit AF lenses. If they are not AF you will lose autofocus and metering.
Do you know that on the D90 the lens becomes a 75mm but the aperture stays the same, so for instance the 50mm f/1.8 is a 75mm f/1.8.

Yes and yes. Bear in mind that not all features may work. You probably won't get autofocus or metering with the Nikon D90, for example.

If the Phoenix lens is autofocus (AF) in Nikon mount, it will work with the D90. You may find that you want to switch to manual focus when you are using it for macro shots for better control of focus. It will still set exposure properly when set to manual focus.

This is a lens for Sony/Minolta cameras. It is not compatible with the Nikon D90. Hence a Teleconverter for Nikon will not work on this lens to mount it to a Nikon D90.