as 106pete says if you've never done this before don't even bother.
it's not difficult to install helicoils...i recently heli-coiled a pair of 4-pot brembo calipers for a mate as all the lug threads were completely screwed.
me and the old man did it on a a bench drill to keep it absolutely perfect and managed to get the coils installed spot on.
however, upon installing the caliper and going through the bleeding sequence, one of the nipples decided it no longer needed to be attached to the caliper and snapped off in a cloud of swearing, cursing and general shouting.
a bleed nipple is a lot tougher as it has a conical base the nipple presses down onto and during very careful drilling we nicked the cone at the bottom meaning no matter what we did it continued to leak. we ended up sending it to a pro company who do it on a jig & CNC machine to precisely remove enough material and size it up....cost £60 i think.
as for removing the piston and seals they are a piece of cake...if you have a little air compressor that is more than enough pressure to blow the piston out and then the seals are a doddle.
if you don't have an air compressor....you need one
