A lot of six-day (and other madison) riders use road bars for comfort. It's also nice to have road bars that have a real "top" position when you're riding relief. For a 30-40 km points race they're going to be a lot more comfortable than steel sprint bars, too.

I have a couple or three 70's and 80's steel track bikes and IIRC (since they're at home and I'm not), they all have at least slightly elliptical fork tubes.

A lot of guys are also riding 170s, and even 172.5 on the track, particularly if they ride shallow tracks or are primarily pursuiters. I pretty much stick to 165, but I also get called old school.

The main reason anymore to use 1/8" chain is compatibility. 3/32" stuff is quite strong, and as mentioned above, nobody skids on the track except as the consequence of something else already being extremely wrong. At that point, the last thing you need to worry about is 1/8 vs 3/32.

Now that almost all forks are threadless (even on track bikes) you mostly see alloy stems, even on the very highest end bikes. They seem to work fine.

Track headsets probably take much less of a beating than road headsets (except when they're on the roof of the car on the way to the track). A lot fewer potholes on most tracks. Again, there's nothing really track specific about headsets. The only time it will matter is if you're racing keirin in Japan and have to have all NJS stuff.