The localcryptos backup.json file for the BCH wallet

To download the json file is easy. The file includes "chain_private_key" and "first_address" name/value pairs.

What is the "chain_private_key" (in the json file). Is it a seed written in old format?

Why is the "first_address" (from the json file) needed?

Is it a BIP-32 hierarchical deterministic wallet?

If "chain_private_key" is the seed, what is the derivation path?

How can I import the file into Electron Cash for the PC?

Is there another BCH wallet that can import the wallet from the json file?