You can change your name as part of your naturalization if a court in your area conducts naturalization oath ceremonies.

You do not need a lawyer unless you have had certain issues with the police and/or government.

Yes. You should always be honest with Immigration regarding all:

To be able to fill out your citizenship application you will need to bring the following to the workshop:

You should use an "Application for Naturalization" (Form N-400), which you can download here: http://www.uscis.gov/files/form/N-400.pdf.

Send to the service center of the U.S. Citizenship and Immigration Services in your area.
U.S. Citizenship and Immigration Services (USCIS) Service Centers