Mumbai Traffic Police — its not a complaint but need some help to understand things

Address:

Mumbai City, Maharashtra, 400058

Hi.
I hope i am writing at a right place.
Its been many days i find local police constables standing in any corner in our locality and stopping people for not wearing helmet.
I have several queries on this.
I have a car so dont face this problem but there are many instances where i need to ride a bike to travel locally.
Ive read several news articles where its mentioned that a traffic police constable or other constables cannot ask to display insurance papers, puc and other papers.
Now ive seen that this constables who stands alone in any corner doesnt issue any challan just threaten people to take to the police station and charge them for several things.
Now is it allowed for any police constable to stand and catch the bikers on local roads where there are no signals and no traffic flow?
Can they charge on the local roads for not carrying a helmet?
I remember i had a conversation with a friend of mine who is a police officer himself, he stated that there should be a senior officer if the constable is charging u more then rs.100 and also constables cannot issue the fine reciept. Is it true?
I also wanted to clear many things.
1) is there any dedicated boundary till where a localite can travel without a helmet?
2) does a single constable without any senior has any right to investigate or charge people not wearing helmets?
3) can a constable issue fines and issue a receipt on his own where at the end of the reciept a signature of a senior officer is required?
4) are there different charges for not wearing helmet if caught by a traffic police or other police constables?
Many people are not aware and so end up having an argument.
It would be a great help if i get this information from an educated officer.
I hope i am reaching the right place.
Thank you.