Skoda Octavia VRS Pads, discs and drivers door not opening off key fob

Hi Can anyone tell me how to change a 2002 discs and pads, do I just take the slider off or does the caliper have to come off as well.

And what tool do I need to wind the pistons back, is it the same as for the Mark 1, the lazer1314 tool?

And why do you only need it for the rear? And to use the tool the caliper would have to be off or the disc removed is this correct?

Also my drivers door is not workin off the key fob, all others are just not the drivers door. Works fine with the key, and the alarm light is not comin on either

Thanks

I hope someone can help, its doin my nut in now, and I,ve got a bust front spring DOH