That WiFi shield schematic is relatively normal and the LCD one can be worked out...
Look on the right side of the WiFi shield schematic. This has all the Arduino headers, labelled with the Arduino pin numbers. It uses pin 4, pin 10 and pin 9. 9 seems to be just a yellow LED, so it doesn't really clash with any other shield's use of that pin. 4 is the chip-select for the SD card. If you have no SD card installed then it won't clash with any other shield either.
This seems like a very small number of pins, until you realize that it's using the ISP header in the middle of the board. That is for the SPI bus, which can be shared on many shields. For most Arduinos, this is identical to pin 11, 12 and 13, so those pins aren't 'free'.
The unusual thing with the LCD is it's actually using the big double-row header across the bottom of the MEGA. But it doesn't label the pins with the Arduino pin numbers. It's using almost every pin there.
CN3 looks like the Arduino 'power' header, where it's connected to both 3.3V and 5V.
CN2 seems to be labelled like it is Arduino pins 0-7. So this shield is using pin 4, although it's not immeidately obvious what it uses it for. TP_DOUT, whatever that is.
On the face of it, these two shields do seem to be compatible except you shouldn't install an SD card in the WiFi shield and the WiFi shield probably doesn't pass through the additional MEGA connector, so you might need some longer pins to make it reach.