Need help w/ pre-calculus summer packet.

I know my title isn't very descriptive, but there are 3 types of questions i'm in the need of help for. I am very appreciative for any help!

Write the following absolute value expressions as piecewise expressions.

1. |x^2 + x - 12|

I know that it's possible to graph it using my calculator, but is there a way not to use my calculator? Half of calculus is without calculator.

Solve the following by factoring and making the appropriate sign charts. Write your solutions in interval notation.

2. x^2 - 16 > 0

I got (4, ∞) but I don't know what a sign chart is.

Factor completely.

3. x^2 + 12x + 36 - 9y^2

Stumped. I know I can factor out an x but not sure how that would help.

I appreciate any help. Look forward to hearing from people!