Change font color when posting new iCal events
The calendar app doesn't give you that level of flexibility. Apple has designed it to look a certain way, and that's the way it's going to look, bar some pretty serious hacking. Busycal is a calendar app that does use the calendar's color for the text, not just for the dot.
The "Birthdays" calendar is a special one automatically generated based on the birthday info you enter for your contacts. You can't edit it directly.