NANO 33 BLE project-questions

Hello everyone,

I am new to the world of MCUs and how to work on them. I got a project as my thesis.
In my project I will use Arduino NANO 33 BLE, MAX86146(for PPG and HR),KX122 (needed for MAX86146), MAX30003( for ECG) and MAX30208(for temperature).
For my power, I have decided to use 2 MCP1700 and 1 MIC2877 voltage regulators.


I have some questions.
1)MAX86146 needs an Accelerometer in order to make correct measurements. I know that Arduino Nano 33 BLE have an integrated IMU, which I understood that I can access through the I2C, but MAX86146 is designed to take the Accelerometer measurements through SPI, that is why I added the KX122 Accelerometer, is there any way to take this measurements from the IMU of Arduino board?
2)This device will be placed on the wrist(Device 1). There will be another device placed on the leg(Device 2), which will have a GPS and another MAX30208 for temperature measurements.
Can Device 2 send data through BLE to Device 1, and Device 1 send data through BLE to an android phone at the same time? To rephrase that, can one device receive and send data through BLE simultaneously?
3)The MAX30003 has an external oscillator which needs to be connected to the MCU. I know that Arduino NANO 33 BLE has an internal oscillator, can I access that oscillator through Digital Pins?(that is the dotted line)

I have already posted this(plus some questions) on the Project Guidance sector but they redirected me on this sector for better answers.
Feel free to add any comments or suggestions or point out any mistakes!
Thanks everyone in Advance.
Orestis V.