Arduino Uno + Ethernet Shield + wireless transmitter (both on SPI bus)

Using Arduino Project Guidance
#1

I have a working understanding of using two devices on SPI at the same time - basically they share the MOSI, MISO, and Clock pins, but each device needs its own CS (cablet select / device select) pin. The Ethernet Shield is kind of stuck with pin 10 as the device select pin, right? I can't change that? That's fine, I can change the device select pin for the wireless transmitter. No problem.

  1. The ethernet shield uses 5V for power, right? Does it get that power from the 5V pin along the sides or the ICSP header? Sparkfun notes say the ethernet shield uses the ICSP header, but the ICSP header doesn't have 5V power. Trying to understand how it's designed.

  2. Can I use the ethernet shield's female headers almost like a prototype shield? That is, connect the wireless module's SPI wires (Device Select, MOSI, MISO, Clock) directly to pins 10, 11, 12, 13 on the Ethernet shield?

Thanks!

#2
  1. The ethernet shield uses 5V for power, right? Does it get that power from the 5V pin along the sides or the ICSP header? Sparkfun notes say the ethernet shield uses the ICSP header, but the ICSP header doesn't have 5V power. Trying to understand how it's designed.

The ICSP has the SPI data lines (MOSI, MISO, and SCLK), 5v power, GND, and RESET.

  1. Can I use the ethernet shield's female headers almost like a prototype shield? That is, connect the wireless module's SPI wires (Device Select, MOSI, MISO, Clock) directly to pins 10, 11, 12, 13 on the Ethernet shield?

If it is an Uno, yes.
If it is a Mega, no.

#3