Hi, @surajTLabs! And welcome to Heroic Labs forum!
For 1, it is currently on our backlog a set of improvements on this kind of documentation. More users have similar questions.
For 2, you can find documentation about ticks here.
Also, I found a similar question that has been asked here in the forum and will probably shed some light on your specific Nakama usage: Multiplayer game with physics - #2 by novabyte
Best regards,
Caetano