Not sure on the vintage flashes, but they often have trigger voltages that are unsafe to use in the hotshoe on modern DSLRs.
Those lenses will mount fine on any Nikon DSLR; any Nikon F-mount AI lens or newer will. If you want to mount non-AI lenses, they only mount on the D40/D40x/D60, since those bodies have a recessing max aperture tab that doesn't interfere with non-AI lens mounts.
One more thing: non-CPU lenses (like the two Vivitar lenses you mentioned) will only meter with semi-pro models, like the Nikon D300, D200, D3, D2x, etc. That means if you mount non-CPU lenses on consumer level bodies (D90 and lower), you can only shoot in "M" full manual mode. You might already be used to full manual shooting if you're a film shooter on an FE2. Use the dial on the camera to set the shutter speed, lock in the aperture using the ring on the lens, and shoot. Digital provides instant feedback, so you can check the review screen and the histograms to see if you correctly exposed your picture.