o:O are ya kidding me? Nothing will happen to ya in Finland,its very safe place.Except train station in helsinki at nights tho

Some trains might have showers,you have to check VR's website.But im pretty sure that they dont have it.At least the ones i've used havent:P.Night trains are not modern.They dont have wireless net for example.
I dont think you have to use night train.Helsinki-Oulu takes 8 hours for example,it cant be different from Turku-Oulu,and from Oulu,Kemi is 2 hours away or something.Just wake up early and jump on the train:P
Nothing to see in Kemi btw,just a note.
For train services:
Passengers - VR