Hi, I have many nub 
and burning questions about the nRF52 Bluefruit board. It's such a great board and I'm enjoying learning using it. I would really appreciate some enlightenment here.
So I have a nRF52 Bluefruit board. If I understand correctly, it has softdevice S132 (from Nordic), and it contains the BLE 4.2 stack.
First question(s): Why does it not require a Segger J-Link physical device to update its bootloader? What is the actual physical J-Link doing (costing a great deal), that the Bluefruit board does, seemingly within the nRF52x module without any external chips? What does other SoCs lack that require this additional J-Link physical programming attachment?
Second question: I'm following the guide to upgrade Bootloader in order to have BT 5.0, as per
By simply upgrading the bootloader from 0.5.0 to 5.1.0, did I actually upgrade the Bluetooth stack to 5.0? Because I did read that the stack is contained in the bootloader. Did this really include certain functionalities that are uniquely for interacting with BT 5.0 (if there are any)?