Your various questions require different answers. This is not really the forum to answer all your questions in detail. You should consult with an immigration attorney who can learn more about your circumstances and be able to answer any questions you may have.
The above information does not constitute legal advice, and is intended only as general information. You should speak with an attorney to discuss your individual case, as not all facts are known at this time.
Generally, you can apply for your U.S. citizenship 4 years and 9 months after being a permanent resident, as long as you meet all of the other requirements, such as good moral character and residing continuously in the U.S., as well. As a permanent resident, you can petition for your unmarried children and your wife. However, the process will be faster once you are a U.S. citizen. Finally, you may qualify for a fee waiver for the citizenship fee if you are receiving certain public benefits. I suggest you have a consultation with an immigration lawyer who can review your case in more detail and give you a better idea of your options. If money is an issue, there are often non-profits who help with citizenship applications for free or low cost.
The information offered is general in nature and not meant to be relied upon as legal advice. No client-attorney relationship is created through this information. Please consult an attorney prior to making legal decisions.
It is important that you consult an immigration attorney. Although you will be eligible to apply for citizenship after having permanent residence for 4 years and 9 months there are other important factors that determine whether your application for citizenship will be approved, i.e. any criminal record or unpaid taxes. Once an immigration attorney has assisted you with the citizenship application if appropriate, they can also assist with your other questions.