The old flashes for film cameras simply cannot do iTTL on digital. They were made before digital iTTL was invented.
Don't know about damage. It zooms, so reasonably modern, probably is OK, but you can measure it simply. Just turn it on (not connected to anything), and measure the DC voltage between the foot center pin, and the metal contacts for the shoe frame. Probably in the ballpark of 5 volts, which is fine. The Nikon DSLR can handle up to 250 volts. The danger scare was mostly started by a few Canon EOS models that Canon said could not accept higher than 6 volts.
Be careful of your eyes when measuring, it could flash when touching the foot pin. Do NOT place it face down on anything that can be scorched. No big deal, just aim it away from you.
If the flash has a remote triggerable Manual flash mode, or an Auto thyristor mode (non-TTL auto), those functions can still work.
But - Times change. Digital cameras mean that it is time to get a new flash.
If you don't want to spend much money yet, look at
http:///www.scantips.com/lights/vk750.html
It won't do Auto FP HSS, or be a Remote for the Commander (which the D700 camera can support), but it will do all else, will be a regular flash.