Programming Graphics Help

I am going to attempt to write a game in OpenGL that is a 2d Side scroller like Gunstar Heroes, Sonic or what not. I am wondering if it would be quicker to get a tool that is a level editor or program one, rather than make quads in OpenGL and texture map all of them for background, sprites, and all other graphics? I want it to be more than just a simple ground and sky as a backgroundm so, would the most efficiant way be to get some kind of level editor like they use for some games or make one, or just texture map all of it? How was the most common way companies would add the backgorund in on game like on the sega genesis and super nintendo where thier was a lot of different background sections (i.e the sky the mountains the trees the ground)? Also i have seen their is a way to program tiles bby having a tile of all the level in squares on one bitmap and give it a number or value and tell it where it goes by programming it like this { 3,3,3,3,3,3,3,3,3,3,3,3 // sky (the # 3) 3,4,6,7,7,7,7,7,4,3,3,3 // sky (3) and clouds, (4,5,7,8,9,6) 3,4,5,5,6,7,8,9,3,5,7,4 // sky and clouds again }