Andreas Antonopoulos has a YouTube channel, so if you can't read his book, watching the videos will give you basic and fairly good information.
I will leave you the channel link at the end.
- I also want to be able to create a wallet where it changes from a 2-3 multisig to single signature after x months
I don't understand what you're trying to say here or why someone would need code like that, but in short, if you're looking for a time lock feature, you can try it here.
https://coinb.in/#newTimeLocked- I also work in Finance and SQL is required, that's why I want to master this too.
This is something different and I don't think you will learn it in a short period of time if you don't have a background in it. Perhaps it is better to buy some Udemy videos.
https://www.youtube.com/channel/UCJWCJCWOxBYSi5DhCieLOLQ