Hello Vikram,
I usually go the command reference where there is a paragraph default that explains if the command is applied or not by default.
The difficult part with command reference is to find the right one.
You can use the command lookup tool to locate the command reference name then you open the command reference and look for the command.
b) my understanding is the following:
introduced: first IOS release where the command /related feature has been introduced usually an experimental or specific one (T train or others)
integrated: mainstream IOS release where the feature becomes part of main features and you can expect it in later releases
Hope to help
Giuseppe