Help for an old friend...
Your friend will need either a D200, D300, D700 or D2-series camera to gain metering with manual focus Nikkors. The lenses will need to be AI or AIS manual focus lenses (which came out the year the FE was released but the FE was also capable of taking Pre-AI lenses too).
AI and AIS lenses will mount but provide no metering with anything less than a D200. When focusing, the AF sensors will track the focus as you turn the ring and a small green light will confirm when the camera thinks that your lens is manually focused correctly.
There is a company that sells customised focus screens for DSLRs that provide manual focus aids (the classic split and microprism collars) for most Nikon DSLRs. I haven't used one personally but I am toying with the idea. This should improve the manual focus feel and efficiency up to a level comparable to what your friend would be used to with the FE.
I have the 105mm f/2.5 and I think that's worth retaining for use on digital, haven't tried the 50mm f/1.8 but I think that has the same optics as the current AF-D version. As for the 24 and 28mm, arguably there are decent kit zooms that'll do the work of those two and would make a cost-effective, convenient and relatively lightweight package with a D40 or D5000.