Can I bring her here, together with the baby, and does it take long and does the baby make things easier at all?

As a lawful permanent resident, your petition for a spouse can take years, because she is subject to a visa quota enacted in 1990 as the spouse of a permanent resident (See Visa Bulletin for F2a category). You should seek U. S. Citizenship as soon as you can qualify. However, your son may be able to secure a U. S. Passport and enter the U. S. As a result, I strongly recommend an appointment with a competent and experienced immigration attorney, who can take enough time to ask enough questions, explain matters, and provide enough legal advice to your satisfaction. The above is general information, not legal advice, and does not create an attorney client relationship.

Generally, a Permanent Resident (holder of a "Green Card") may sponsor a spouse (but not a girlfriend or fiance) to obtain immigration benefits in the U.S. through consular processing. The facts that the couple has a child together and that the child is a U.S. citizen by birth do not have any impact upon the application eligibilities, but that certainly would be evidence of the couple's bona fide relationship. It would be wise for you and your fiance to consult with an immigration attorney who, after learning all of the relevant information, could advise about eligibilities, options and strategies, and could offer legal representation in the often complex application process.