Programming 2d games

Unless you want to go with a pre-built engine like game-maker, SFML is as good of a choice as any. Games take time; Braid is a 2d platformer and it took 3 years to create. At least with SFML and C++ you're learning transferable skills.

Some tools you should consider before moving to a 2d side scroller: Will you be using tiles for your maps, and, if so, how will you create the maps? I'd suggest using Tiled. there are a few C++ Tiled map parsers you can use as well (you can find the links from the Tiled page).

Also, I'd consider using a 2d physics library (chipmunk-physics is what I use, but box2d is also popular) to handle the movement and collisions in your world. You can check out my Old Blog (linked in my sig) for a game I made using chipmunk-physics.

Good luck and have fun!

Speed comes with experience. It should go without saying, but the more you program the faster you will become at it. With experience there will be less trial-and-error and you will spend less time figuring out how things work. Of course, you could use pre-built engines and libraries to speed up the development of a game, but at the same time you would be losing the experience you would have gained in creating those parts of the code yourself.

There is nothing wrong with using something like Gamemaker to make a game, as long as the tool does what you want it to. That assumes you are interested in the final result and not the process. It's like riding a car to work. It's much quicker than walking, but you won't get the exercise from walking, so if all you want is to get there, it is fine.

You can try html5 and javascript. There are even books on the topic. Simply search html5 and games in amazon.