Bands will almost invariably be performing in dimly lit conditions, so a fast lens (big maximum aperture) will be an advantage. I see from your gallery that you use a Fuji S5600, which appears to have a max aperture of f/3.2. This is reasonably fast, so you're onto a good start there. In the dimly lit pub (or wherever it is that your mates are playing), you may find that in order to get a reasonable shutter speed, you will still have to bump up the ISO on the camera. This will result in noisy, grainy images, but they can be cleaned up using Neat Image, or similar.
Using the flash will give your pictures a very different feel, and useless unless you are right up the front, the built in flash simply won't have the ooomph for anything beyond about 10ft. It all depends on what kind of image you're after. Motion blur caused by low shutter speeds may well convey the energy of the band, it may just look like you've had a few too many beers.
A good idea would be to go along to a rehearsal session, even if it's not in the gig venue. Experiment with different camera angles, different positions, different compositions. You will learn much, whatever the results. Have a look at magazines showing photos from other gigs, think about the compositions that work. I don't think you'll find many shots taken from a straight ahead position, with the stage horizontal, and the band standing stiffly in the middle.
