JEDI-SDL provides several functions for software blitting, addition/subtraction blitting and alpha. it is all in software and as such eats processor cycles.

For new stuff, you really should consider using 3D Hardware functions using OpenGL or DirectX as software 2D isn't quick enough.
Hardware copes with thousands of particles with utter ease compared to software. Also, decent rotation and scaling is available for free.. without slowing down the renderer.

If you don't think you can spare the time to learn about using the 3D stuff, then you can use the JEDI-SDL stuff. But be aware, it is a crutch. I still haven't made the leap to 3D for 2D and I really should have... and the longer I put it off, the less likely it is that I'll do it.

it sounds to me that you want to make some impressive visuals, I'd take the plunge and go hardware if I were you, better that than have to re-do all of your hard work when you realize you need better performance and can't get it.