Laws and Punishments & Authority of Police

I just want to know how to 'refer' to IPC. For example, let's take "Public Nuisance". Section 268 of IPC just defines what can be considered as "Public Nuisance". Where can I find what is the punishment associated if proven of having done an act of "Public Nuisance". Secondly I want to know what is the level of authority Police have. For example, under the same section mentioned above, can Police themselves file an FIR on any Indian Citizen? Or is a complaint from some other Citizen (who dwells in the vicinity of incident and have affected by injury, obstruction, danger or annoyance) is mandatory to file a FIR? For what kind of crimes, does Police have the authority to keep the accused in their custody till they produces him on court? For crimes whose punishment is associated with just paying some fine, can the Police keep the accused in their custody till they produces him on court? or Can the accused walk out of Police Station after getting a copy of FIR and come directly to court to pay the fine? Is there any law that prevents the Police from keeping the accused in their custody if the accused is a female? For cases whose punishment is associated with paying a fine, will the case have a Judge's hearing? or Does the Policemen's decision is final? If there is a Judge's hearing, and if the accused is denying that he committed that crime, should Police need any witness to prove the crime? Please give me references to "books" and "websites" from where I can get these kind of information.