Zina (Adultery)

Q: I have few questions regarding adultery/zina.

1. How we define adultery/zina in Islam?

A.Generally speaking zina is generally defined by Islamic Law as unlawful sexual intercourse, i.e. intercourse between individuals who are not married to one another. Further, we define intercourse as sexual contact between individuals involving penetration, especially the insertion of a man's erect penis into a woman's vagina, typically culminating in orgasm and the ejaculation of semen. 

Please correct me if any thing written above is wrong.

2. If a man insert his penis into women vagina but not completely and also did not ejaculate semen in her vagina but outer part of vagina. What should we call this? Is it adultery/zina or not?

3. If a man does sex with the woman or women with their agreement. Sex include kissing, breast sucking, anal sex, and oral sex. Either it will
fall in the category of adultery/zina?  Although it is understood these are all sins. but I need the most precise answer regarding adultery/zina.

4. Can a man marry with woman with whom he had adultery/zina?

5. Either there is any relation between a man earning and adultery/zina? as some people say that if one do adultery/zina. Allah decreases his earning?

6. Some people say that adultery is something which one borrows and one of his family members has to return it. Is there anything really written in Islam?

Thank you for your time. I hope you will answer my question at your best according to references from Quran and Sahi Hadith and earliest possible.

Q: I need some information on adultery. What is the sin of visiting whore houses and indulging sex with a prostitute. What happens to the nikahaa whilst indulging in this?