As far as the legal thing, woodelf, you are 'pushing the boudaries' a smidge. Specifically, you can't include character generation rules...note that the SRD doesn't really mention XP, level advancement, when you get feats, how to roll ability scores, etc.
That is the legal requirement for using the d20 logo and the "d20 system" copyrights. Otherwise, you can't legally claim your thing to be part of the d20 system or use the d20 logo.
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You can't use "d20" if you're presenting character generation rules or advancement rules, effectively. You can make it OGL....but in the case of the SRD, duh.
I mean, IANAL, but this is my understanding. Even if your rules are different from the PHB's, simply including them would be enough to exclude you from using the d20 logo or mentioning the d20 system...I could always be wrong, though.