Trains are automated, but there are attendants at the doors to make sure nothing stupid happens. Much like other indoor areas, there's a rough floor mat inside each doorway that you're expected to wipe your paws on. There's a central aisle with a long bench on either side meant for perching. There are vertical rails at intervals to wrap the tail around for stability. On higher capacity trains there are two levels of perches but no second floor, so you have to climb up to the higher perches. Even ignoring the crush of passengers, Humans find the interior cramped and ill suited to the human form. They end up having to sit on the floor since the perches aren't designed for the human rear end. Lighting may be outside the human visible range.
I'd probably say just "birth" rather than "rebirth", but it certainly scratches a lot of the same cultural itches you'd expect from a human holiday related to or occurring in spring. Perhaps even more so for the yinrih given Yih's ring and larger tilt resulting in increased seasonality. There's probably a seasonal greeting like the one for the winter feast, but I haven't come up with one yet.
They certainly have special prayers and hymns. Not sure about more secular songs, as I can't think of a custom that could be commercially exploited a la Christmas presents. Maybe you see sales on things like fermented steadtree fruit juice around those times similar to the uptick in seafood sales during Lent. I don't think yinrih retail workers have to suffer the same ten songs remixed forty different ways over and over again. Certainly not for the seasonal feasts. Maybe for the feast of the kindling of the fire of understanding since that's the really big holiday before First Contact. ("Yay aren't introspection and symbolic thought just the greatest!" or something along those lines.)
I've given that a lot of thought. If a yinrih were born on Earth in the middle of the 14th century he could still be alive today. I could see yinrih being a boon to human historians in the future. The social dynamics surrounding the vast difference in lifespan are fascinating, but I haven't explored them fully. I imagine that would make politically integrating the two species difficult. The yinrih might have a hard time coping with how fast human culture shifts and cycles. On the other hand, the yinrih think nothing of starting projects that would take an entire human lifetime. It's possible the two species stay largely separate, only engaging on a personal level after the initial massive cultural exchange following First Contact. I think there will be human enclaves in the Spacer Confederacy, and Hearthside will bend over backwards to get human settlers, but otherwise I don't know.
One of the reasons for having human enclaves at Focus is that Earth governments scrupulously regulate the introduction of monkey fox tech into Earth society. The economic impact of a K2 civilization just showing up and handing over all their stuff would be earth shattering, causing a lot of harm in the short term even if we benefit overall.