Yes.. I do it so often, you'd think I have OCD.. I didn't do so in the beginning as I didn't know how and when my computer crashed, I lost quite a bit..
Yes, I do. I use ZenOK online backup it saves my files automatically, besides 2 gb for free works really good.
Yes I do, I backup everything not just graphics, but all my site related files. I put them all on my USB Drive