For the :Snappy and Dashing ;D : Go to your settings under your name at the top of your page and it is called your Comment Signature.
For the pics, such as:
and
Those are icons that are uploaded onto dA by other Deviants, in the beginning of each one you have to type :icon and at the end you have to type plz:
Example:
is made by saying :icon at the beginning, and then icecube in the middle, and plz: at the end. No spaces.
And if you see an icon you like, just put your mouse over it and it will say what the icon is called.
This one
is :icon epic stare plz: with no spaces.
And this one
is :icon epic face plz: with no spaces.