sarea | question about taxes

Okay, bear with me, because this is the first year I've done my taxes completely by myself (previously, my dad did them, or looked it over after), and I really know very little about it. This was also the first year that I filed online (couple weekends ago), and I'm nervous because I asked to have my refund deposited into my bank account, but so far there's been nothing. I'm only worried because supposedly doing it that way makes it happen faster, but now I'm imagining a worst-case scenario in which it hasn't been filed at all.

So my questions are:

1) Does the IRS issue refunds before April 15, or can it be at any time? How can I know for sure that they've received my tax return? Since it's April 14, it's not too late for me to mail out a copy of my return tomorrow if I need to ... should I do that just in case, or am I worrying for nothing?

2) What happens if you don't file on time? Does that mean that if you were expecting a refund, you can kiss it goodbye? Or since they don't know you're supposed to get a refund, do they come after you and go, whereTF is your tax form bi-ach?