Hi,
I did my fronts a few months back, personally i never removed the cap from anywhere to allow expansion I just changed them then reset the piston. The brake reservoir tbf was bordering on minimum before I started so it just seemed to top up a little but within the min/max range.
Pads I got mine from andrew page standard Bosch about £25.
Jacking have a peek under car and you can see where the jack bit will connect too, there is like a gap in the jack where the underside drops into, it's quite obvious when you see it.
Once there done though just remember to give the brake pedal a few good pumps to get the pistons biting again before you take it out!
Then when you have it out do a few hard stops from 30 to get the pads grinded into the disc ...