Instead of a user having to type in a combination of brackets and letters to get italics in their question/answer text, why not have a small button sited above the text box, next to the Youtube URL box, just like you get in a word processor. With the space available you could have several - bold, italic, underline and maybe a couple of colours.
Lots of people use a word processor or text editor and so would readily understand how use such formatting buttons.
Forget smileys, who cares about them, but you don't have to use formatting if it were available but there are times when it would come in useful. I would definitely use formatting to enhance replies to some crossword questions.