As for your understanding of how LLMs and compilers work, it does not match my experience working on either one, back in the day. I humbly suggest reading some of the literature on reproducible builds, as well as the conditions under which LLM inference is/isn't deterministic, as it is more complex than most people understand.
No they don't. They refer to the weights used for weighted sums. The weights don't have to even between 0 and 1.