Hello, Florian.
Welcome to the list!
I watched Bruce's video a while ago and I can not remember what those acronyms stand for.
As for the 15k, that means how far in k (k A-1) he collected his EXAFS data. You're missing an important information: E (eV) ~ 3.81 k2. Now, do the math! Hope that'll make things more clear to you :)
As for the k steps, 0.05k, that was the way he collected his data, in k-steps, instead of energy steps. I usually collect XANES data in E-steps and switch to k-steps to collect EXAFS data.
I'm not sure if this is a proper venue to make advertisements but Scott Calvin has recently published an excellent book on XAFS, XAFS for Everyone, and I would suggest you to refer to it at your earliest convenience, so you can work on your "backgrounds" more effectively :)
Good luck!
- Dalton