Sikhism on Divorce and Re-Marriage?

No, but this implies that the couple is really married. "They are not said to be husband and wife, who merely sit together. Rather they alone are called husband and wife, who have one soul in two bodies." (Guru Amar Das, Pauri, ANG 788) If it is a true marriage in which both partners are completely blended into one, then work it out together. Merely going through a ceremony does not make you married! You must live it or it is not real.

It is not adultery that breaks the marriage. It is the loss of trust. There is always a way through, the question is, "do you want to do the work necessary to make it through?" If not, then why do you think a second marriage will be any more successful? Marriage takes a lot of work, communication, compromise, shared spiritual life and a constant building of trust. Under extreme circumstances (constant emotional or physical abuse) Guru Ji understands that the karma is being paid and that the marriage may need to end. Under extreme circumstances you seek help.

Sometimes a marriage turns out to be what I call a "karmic marriage." i.e., karma got paid through the pain of a relationship that never became a true marriage. In this case, divorce and an honest talk with the panj piyare and the reaching of a common understanding comes next. Remarriage is a chance to create a true marriage now that the karmas have been paid. If you can understand and live the Lavan then you have a chance at this.

Yes, a woman past her first trimester can go through the Lavaan. It is only two people getting married. The soul inside is a part of the mother and has no will of its own during pregnancy.

These links may help you further: What is the Sikh Attitude to Divorce and Adultery In Sikhism.