I would say for stock racing, a battery closer to the lower 4000mah range like the 4100mah packs from Protek would give you a nice weight savings with more than enough mah even when charged to the 8.4V limit (assuming you are running that by you). I am also a fan of promatch batteries. Great packs for the money. A good all around pack mah size though would be the 4900mah like someone else mentioned. I am rocking fat boy 6000mah packs for now but will probably make the switch this summer once we know what we are doing for our classes.
I would agree that an bit higher end ESC like the Tekin Gen2 or Hobbywings XR10 Pro-stock ESCs will give you more options. I believe both of those ESCs offer high voltage BECs, which I would want at a minimum personally. If you are going high end but focusing specifically on stock, the Tekin RS Pro Black Edition would offer that to you. As I am unsure here what we are doing for classes, I went with all Tekin RSX Pros. Bit more flexibility. Before that change, I ran all Hobbywing XR10 pros and then before that Maclan MMax Pros, with some Picos for the kids
As for the hobbywing xr10 just stock, we swapped to a better capacitor and that helped with punch and breaking with that ESC. Funny thing is, for the money there is a quicrun esc that appears to be the older V2 model of the hobbywing pro speedo that is about the same price. So on the cheap, it could be much better than the xr10 juststock if you want options for hot motors.
As for charger I would also recommend the Icharger line too. Been quite happy with mine even though I don't do much of the high charge / discharge cycling as haven't found a need at this time. but its nice to have the option.
As for motors lots of options out there. So far first runs on the Tekin Spec-R I have been happy with it. On the cheap my previous motor the Surpass V4S was quite nice, very torquey. Maclans V2 was also a nice motor too. Lots of options there..