Clock source

Dear Dialog,

I'm now using DA14580 with external 16MHz (for main) and 32KHz oscilator (for sleep clock), but today
I found following description in the datasheet.

"There are 3 RC oscillators in the DA14580: one provid-ing 16 MHz (RC16M), one providing 32 kHz (RC32K)
and one providing a frequency in the range of 10.5 kHz(RCX)"

Q1: Does this mean I can eliminate external these oscilators?
Q2: If Q1 is yes, modification of FW is just changing the clock source selection of CLK_CTRL_REG?
Q3: Regarding CLK_CTRL_REG, where in the FW I should change this register? At the top of user main_func?
Q4: Even if internal clock source is used, specification about SCA(sleep clock accuracy) or other requirements
会见the BLE regulation?

Best Regards,
yukio