Entity Extraction & quotas

Hello Team,

I am working on analyzing yellow.ai for developing chatbot. so would like to know below information

  1. for basic subscription is their any limit to create intents, entities and bots ?
  2. How entity extraction is done - Whether entities are extracted using rules or machine learning techniques.
    3.When we compare Yellow.ai with other market players like Kore, MS bot, Lex, Google dialog flow how the subscription/pricing model work.

some how I did not find this details in documentation. Also do you have technical document of NLP used for chatbot ?