Why grease the pan, then line with greaseproof/parchment paper? Many recipes I've seen request this.

Is it just to stick the paper to the pan to make it easier to work with?
Greasing and lining with paper is something of a belt-and-braces approach to simply ensure the cake doesn't stick to the bottom of the tin. I have several recipes that go one step further and suggest greasing the paper as well afterwards. As you suggest, greasing the tin first also stops it from curling up.