Thanks a ton! And yes, Audacity is one of the easiest way to compile the individual parts, if you don't already usually use another audio editor!
I've been thinking for a while that it'd make sense for video game music packs to feature variations of themes and layers to allow for the implementation of dynamic music, which is a huge part of video game audio. I haven't stumbled upon other asset packs that do that yet either. I'm sure I'm not the first one to do this, but it's rare enough that you and I haven't heard of it, at least ^^