I suspect the colors don't mean much of anything ... except perhaps to the folks who manufactured it.
If I'm understanding you correctly, you've got a wallwart with a USB output, and an adapter that goes from USB to a PSP DC power input jack. I have a similar setup that I've used to charge my 500 (which has the same connection/charging requirements as the 505) quite successfully several times. And yes, mine will charge through the DC in jack from a regular USB port as well.
I suspect that as long as the adapter does, indeed, fit the power connection, you're probably fine. One way you can check it is to see if it'll fit a PSP -- those are a lot easier to locate than Readers are. You probably know people (or their kids) that have them, and you may be able find one in a store on display. All you have to do is see if your plug fits, if so you're probably in good shape.
