can I bookmark a question?
Doesn't seem this is supported yet. Would be useful to have
You can favorite a question, which is I guess what you mean. There's a little star below the thumbsdown that looks like this:
Clicking on it adds the question to your favourites, which can be found in your profile under "favorites".
Otherwise, if you just mean add a bookmark in your browser, CTRL+D works nicely :)
To enter a block of code: