2 Questions - Wireless communication and SD card

  1. Let's say I have an SD card shield

OK. You have a SD card shield.

How do I program the Arduino to play that sound by it's name?

First, you add a Wave shield. Then, you move the SD card. Then you use the library that comes with the wave shield to play wav files.

Or, you get a Rogue Robotics shield that can play other types of sound files.

The Arduino can not decode any type of compressed audio file, and does not do a particularly good job reproducing sound anyway.

What is the code for the other one? I mean,
if that pin is HIGH, than delay 1mS, than LOW and another delay.

The first thing you have to do is read the IR receiver, and see if it is receiving anything.

what if it's a big condition?

Then you use big parentheses.