If you want ESP32 to consume little current while using BLE you'll need to use light sleep, which requires the 32k external crystal. Here's the documentation on it: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/power_management.html#dynamic-frequency-scaling-and-pe...

You need either a USB-SERIAL board or a ESP-PROG board (that has a usb-serial converter). I could do it by using the serial pin header close to the ESP32 (at it's left). Apart from the GND, TX and RX, you'll also need to connect RTS to EN and DTR to IO0. These are the same pins the ESP-Prog uses, btw

It's not possible due to hardware limitations. You can find the following claim in the espressif website (https://www.espressif.com/en/news/BLE_5.0_Certification): Due to hardware limitations, ESP32 does not support such functions of Bluetooth LE 5.0 as 2M PHY, LE Long Range, and ADV Extensions. Ano...