Welcome! I've broken up your question into two parts – resources on best practices and KPIs, and configuring search.
Elasticsearch e-commerce best practices, KPIs, and metrics:
There's some great content from existing e-commerce users. I've added a couple links below, there's content there about using Elastic products for e-commerce, KPIs, and monitoring:
Creating search configurations:
For Elasticsearch, there are tons of resources around text analysis and creating basic search queries. Here is a getting started webinar with the basics.
It's worth noting there is going to be a base level of technical knowledge needed to reason through configuring Elasticsearch. But there's an alternative! Elastic App Search is built on top of Elasticsearch with pre-built tooling for search use cases like e-commerce. If you're looking to dive in quickly and need comprehensive search configuration tooling without technical Elasticsearch knowledge, it may be a good choice. (App Search is the product of choice for the Honeywell presentation linked above.)
If it's useful, this quickstart should cover everything from ingestion to search configuration for App Search.
Hope that helps!