We could discuss the following questions:
1. Was it possible to generate private keys using OpenSSL in Bitcoin’s early days?
Yes. In fact older version of Bitcoin Core (back then it was called "Bitcoin" and "Bitcoin-Qt") had OpenSSL dependency.
5. Are there any previous discussions on Bitcointalk regarding deterministic private key generation in Bitcoin’s early days?
Yes, here's an example
Deterministic wallets. You can use
https://ninjastic.space/search to find other relevant discussion topic.