Child Support Question in Illinois-Father asking for advice?

Roughly a month ago my son's (1 1/2 years old) mother and I separated. Up to that point, I was a live in father/boyfriend and supported my family 100% since she was pregnant; all income came from me and my employment. Now that we have separated, she has decided to file for child support even though we have agreed on a payment arrangement which is more than Illinois's requires 20% post tax if I am not mistaken-she says she does not want to have to deal with me personally regarding money. Seems silly to me because she will be getting less in the end (right?? if I am giving more than the state minimum on Illinois of over 20% post tax?) but my question is this: she told me that she went to court yesterday and I would be "served" before our court date in June to appear. What can I expect? I am keeping receipts of child support payments going forward (I was giving her cash to make her like easier because she does not have a car or a bank account herself, but she refused to sign a receipt so I will begin giving her money orders so it's traceable going forward) but what exactly will take place when we go to court? I mean I have been providing more than minimum support so what will the judge do since I am voluntarily providing for my son? I don't really care how the money gets distributed to my son's mother, be it through me handing her a payment or a deduction although I don't really want the embarrment or stima of being a deadbeat dad of having a "child support deduction" when I have been willingly providing all along. Also at the court proceeding, would this be an appropriate time to bring up visitation discussions? Right now we have agreed on me having my son on the weekends but I'm starting to think maybe it's best to have it official so there is no question as she made a comment recently about how she could not "allow" me to see my son if she wanted to because we had no legal agreement in place if she wantd to "make my life difficult". Yuck. I am so terribly saddened by this whole situation, mostly because I wanted desperately to be a live in dad with a live in mother for my son, something I did not get. Thanks in advance and please offer advice only if you have something useful to contribute, this is a difficult time in my life so please be respectful.