Thanks, Xeny. That helps.
Okay, that second link tells you exactly what to do:
So let me clarify what we mean by attribution. If you republish this content, we require that you:
1. Visually indicate that the content is from Stack Overflow or the Stack Exchange network in some way. It doesn’t have to be obnoxious; a discreet text blurb is fine.
2. Hyperlink directly to the original question on the source site (e.g., http://stackoverflow.com/questions/12345)
3. Show the author names for every question and answer
4. Hyperlink each author name directly back to their user profile page on the source site (e.g., http://stackoverflow.com/users/12345/username)
So, yes, you’re going to have to put those links somewhere on your page(s) so they are VISIBLE.
I suppose the odd line here and there that is common knowledge or common practices could not will be okay (not legal advice), but copying complete code blocks would be bad.
I agree with @DanCouper; write code yourself as much as you can.
If you use code on SO under the CC BY-SA license, you MUST distribute your app under THE SAME license, even if you sell it. Thus, allowing others to share and redistribute your app.