Tune the alpha for hybrid search

We are a paid pinecone user and have a app running in PROD.
What is the default alpha value used in Hybrid search ?

I want to know how the final scoring is given while doing hybrid search. What % weight of score in semantic and what % weight is from BM25?

How should I tune the alpha to get better results between short and domain-specific description which includes alpha-numeric characters?
Ex. CDU,Basic,1U,24A,120V,10u5-25R (7)

Is there any way to interpret the search results to understand how scoring between openai embed and BM25 happened?