I'm using SDL, and it's a 2D platform game.

1. Screen scrolling? Is it like this - you draw a level with a resolution of, let's say, 10000 x 2000 and then while moving the player, you move a rectangle on the background surface and blit it on the screen?

2. Okay, so background is not a problem (presuming that I got this scrolling thing right), so I wanna know about drawing the platforms. Do I draw them all at once with a black (or white, or whatever) background, which I eliminate with colorkey?

3. When jumping, how do I detect if there's floor underneath the player? You don't have to write a code, I'm just stuck at the logistics part.

4. Player sprites. I draw a couple of player sprites in different positions, then I load the first one into a player var and blit it on the screen. When I need a different sprite, I just load a different rectangular position off the BMP file (the one that contains the sprite I need) into the var and blit it on the screen, right?

Hmmm, what else?
I think it's all for now.