What happens if there are mistakes on the application? I sent it in already but have not heard anything back and just noticed yesterday my birth year was 2007 on that application (of course on my birth certificate it is correct and probably on my bio)- i could not believe it! but because of rate increase at end of last month, it was done in a hurry.

Where do i find a survey of what happens next in process?

You might get an RFE for a corrected form, but I wouldnt worry about it too much. If you hear anything about the goof, it may be several weeks because of the pile of cases filed before the fees went up. USCIS is pretty slow to begin with, but getting out letters, etc is taking an extra couple of weeks because of the volume. If you're concerned, you can call USCIS with your case number and speak to a rep about it. I would be more concerned if it was your fiance's DOB that was entered incorrectly.