1. 08800000 is for real addressing. You subtract it so that you can use it in game. If you used a code in real addressing, you would freeze. So you subtract.

2. He's wrong.

3. You do this for every line:
Code:
lui t0 $(First half of your address)
lui t1 $(First half of your hex)
ori t1 t1 $(Second half of your hex) OR addiu t1 t1 $(Second half of your hex)
sw t1 $(Second half of your address)(t0)
At the end, you should always have 1 hook and 1 jr ra. Hook as the very first line, and the jr ra as the very last line.

Hope that helped.