Getting started with esp32

General
2

  1. Pure Arduino code will hardly work because Mongoose OS has a different approach (event-driven), so you need to port your code (in most cases). However, there are some compatibility approaches (see link to another topic with appropriate information) so that e.g. Arduino libraries might be used. But this is hardly advisable for use in a production environment.
    And Mongoose OS encapsulates ESP-IDF, so that you can directly access functions of it. A note: Mongoose OS uses only one core of the ESP32 processor.

  2. AFAIK the commercial license is only necessary if you want to use functions (mostly, but not only, in the OTA environment) which are only limited usable under the Apache license. But @cpq is certainly the best address to ask questions on this point.