Is there any guide to these practices?

Probably yes. Every practice has its own guide probably.

What is your opinion about the legitimacy of these practices?

What kind of legitimacy you are talking about? Define legitimacy?

Do normal Indians like you guys practice these as well?

No I at least don't and can't tell about others. But aghori tantric etc are definitely is not practiced by normal Indians.

And trust me Aghoris are some crazy MoFos you dont wanna fuck with.

I saw a documentary on Kumbh mela and it feels like spirituality is a big part of majority of Indians. Your opinions?

No it's not. They might do believe in God and religion, tantrik jhar phuk etc. But they don't practice it.

Define Sprituality.

They have faith in God or whatever and are superstatious but definitely none are spritual.