Arduino Mega with Ethernet & SD Card

I want to acquire 12 analog channels , store the data in SD Card and transmit over LAN.
I intend to use Arduino Mega with ethernet shield
Please inform

  1. When ethernet shield is used, how many analog channels(out of 16) can be used
  2. Can ethernet and SD work together
  3. Does use of ethernet shield affects analog values.
  1. When ethernet shield is used, how many analog channels(out of 16) can be used

All of them.

  1. Can ethernet and SD work together

Yes.

  1. Does use of ethernet shield affects analog values.

No.