What laws must be observed for online chat?

Question

Chats

Hello. How to organize the legal part for a text chat application.
1) Do I need to save the chat history in the database, in case you need to provide correspondence to someone?
2) What should be tied to the chat (user ip, and something else)?
3) Does the user have to register in the chat? Can the chat be anonymous (login, chat, log out). This is not a social network, just a chat.
4) Do I need to register the chat somewhere in the state registry or something similar?
5) If the chat is directed to any country, is it necessary to do something by law for other countries?
6) Is it necessary to create some kind of message analyzer to detect illegal correspondence (dope sales, etc.). What to do if there was such a conversation, to report somewhere?

Updated: server in Russia, but chat is available for other countries. Or is it better to host outside?