So is this an actual new code base or is it using Bitcoin code somehow?
Meaning did they recode from scratch?
My understanding is they coded it from scratch, or perhaps took some code from Bytecoin, which is the first coin based on that new algo, but it didn't take off for various reasons. Well, at least big chunks of the code should be coded from scratch, as it's pretty different from Bitcoin and its forks.
Monero is still 98% Bytecoin (not
that Bytecoin!)
Bytecoin is 100% new code and has no lines from Bitcoin or any of it's alts.
The Monero team took Bytecoin and started fresh, because Bytecoin was ninja mined!