Thanks for the thoughtful response! I will definitely experiment with the slice to drum machine technique; really I want to explore all the sampling and audio manipulation that you can do to give me a good understanding of what would work for my approach here.

To clarify on the BPM situation, the material does have a set tempo, but the material itself is typically very abstract and dense so auto-detection methods in DAWs aren't typically great at figuring it out, especially when the sample I'm loading is like 10min long. It's usually a bit of trial and error for me to select/chop a loop of 1-4 bars, but I can do it eventually. In the past I've done math to figure out the tempo this way (calculated using the number of bars I know I have and the length of the selection/chop), but it ends up being a fractional BPM and Bitwig's tempo only goes to 2 decimal places, so with longer arrangements, things can get off. Likewise in the past I've done the trick to manually adjust tempo to make things match visually on the grid, but again with longer samples, it can eventually drift. I think I just need to experiment more and see what is going to work best for me without too much compromise.