Relating to the “samples from artist” vs “samples material”?: as specific as possible.
A recording relationship already contains (or should contain) the artist. But in case the recording features more artists and the specific sampled part only features a specific part which only features a few of these artists, additionally adding a relation to these artists is obviously not redundant information.
In case the recording is not in MB (and you are not able to add it due to…whatever reason), “samples from artist” should be fine.
And if you are able to add/find the speech as a work: that could also be a relationship (using partial, I guess).
I think it’s simply up to: add the data/relationships for which you have, or are able to find, a correct reference.
I’m not sure for a sample, it matters a lot from which edit/mix/etc. it was taken, as it is a sample and might not contain any traces of a specific edit/mix/… It is a fragment. But if specific information is provided from which specific broadcast/edit/mix etc. a sample is taken, that should/could be related to, rather than the original recording.
I think it’s all up to: what sources are available to create one or more relationships.