4. No referral code (ref link) spam.
If i introduce an english service by translating in my language, and if i give my ref link, is it a spam?
Yes.
-snip-
Do not make topics or replies just to share your referral link. Whether it's in your sig, avatar, personal message, profile, within the post itself, or tattooed on your forehead is irrelevant.
Edited for clarity.
2. No off -topic posts.
Some posts may not be related with the OP but it may be related the post which in the thread. Is it off topic?
Yes. If you have another discussion that arises, its best to take it to a different thread. If its not spam I see them rarely get removed though. Discussions sometimes take sideroutes and its hard to distinguish that from offtopic posts.