The only known a590 version that isn't supported is 100c. The two supported version (100e and 101b) are higher numbers, so presumably newer and more likely to be on later production cameras. But that's just a guess.
The canon continuous mode is given as 1.4 FPS (
dpreview) , so 1 FPS regular shooting might be possible under ideal conditions. Like almost all powershots, the you can keep doing this till the disk fills up or the battery runs out.
Number of shots per battery depends, but assuming you don't use the flash you should get hundreds on a good set of NiMH AAs (canon say 500, you might get more with the LCD off). If that's not enough, there's an external power connector.
