#1
Im thinking of doing a few EP's of old blues standard and I'm a bit confused on how to credit them, The Music is all original and the lyrics are either purely how it was originally but theres a few that i've added or tweaked some lines.
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#2
Before you record make absolutely sure that nobody still owns the copyright to any of the songs. It could cost you a heap in licensing fees if they are.

Otherwise you credit them as they were originally. It doesn't sound like you're adding that much to them.
And no, Guitar Hero will not help. Even on expert. Really.
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