Questions regarding ZSTD dictionary training.

1: Are there pre-trained dictionaries i can acquire somewhere?
2: What's the ratio of dictionary size and ram usage if there is a "standard ratio"?
3: I setup my zstd:8 to use forced compressions on every fille, and had copilot make a script that takes every larger file to split them into 128KB chunks for the training to train on each chunk, as even if first block doesn't have equal compression ratio, i wanted to take huge game files split into 128KB chunks, and train on each one for every ".bundle" file for instance to achieve the best compression possible.
4: What's the ratio of dictionary size vs ram usage? As i want as good compression as i can on every file i write.
5: Is there a way to parallel chunk training? As at least copilot stated that the training was singlethreaded only, and as i have a 5900x, i want reading and writing to asynchronously compress/decompress files much more effectively and faster.