Well, I'm starting a project to create a 2D online RPG.

Technologies: I will be using C++ and Python (maybe some other stuff for tools, but mainly these for the game itself), I'm considering using SFML as an API to access some things and for taking care of windows for me, I will be developing this game for windows mainly, but intend to make it multi-plataform once I have some nice amount of stuff done. I'm not going to be working on this project alone I will have people to help me on networking, fore example, with more experience than me in this field. I also have people to help me with providing assets for the game - game artists.

A little background on my knowledge:
I have been programming in C++ for a few years and have a good understanding of the language as well as some experience with developing software in it;
As for game programming I have used XNA to make a strategy/platform game with a few friends last year, it was a fairly big project for us, which gave me some nice experience regarding game programming, I have also some experience with creating smaller games using Allegro 5 and C++, I even created a basic OOP game structure and interface to speed up development of small games, which gave me some better understanding on how to manage game loops and where to put everything.
After all that I also had a few months of experience with Direct3D, didn't make anything really big with it though, but it was useful to understand how graphics work a little better.

So, I'm here to get some ideas, and some other points of view on what I have so far regarding what to use for the game:

I think that SFML will provide me with what I need in terms of performance, any opinions on it?
I'm not sure whether to use what SFML gives me by default regarding rendering for 2D graphics, what do you guys think ? I know I can use OpenGL, and I'm not afraid to use it or anything, I just want to know if it's worth to use it for this project will it have a huge effect on this matter or is the SFML API "enoughly" optimized for 2D graphics?

If it is I have thought about extending the sprite class using a pre-render sort of approach enabling using multiple textures and rectangles for any animated sprites I make (for example) and for tilesheets and things like that using a similar approach, any views on that?

I would like to know how good the networking API provided by SFML is, can anyone with a little experience with it give me some feedback on it?

Well, for now I think that's all, thanks