I know that people charge their phones from the power outlets in Indian rail carriages, but I can't get any good information whether it is okay to plug in the laptop into these sockets or not.
Yes, As a frequent traveller in the Indian railways I can say it is quite safe to plug in the laptop. Some sockets might not work at all but with those that work, I have had no issues at all.
Yes, most of the sockets are ok but you should always check if the battery is suspiciously charging too fast/faster then usual, then the socket could be overcharged. It happend to some persons that I know and it messed up their phone battery.