its really nice to see such a well structured, well spelt first post from a new member. :)
i would have thought the sticky piston could be sorted by pumping the brake lever whilst spraying a thin lube (GT85 or WD40) onto the piston body. if this doesnt work, you may well need to take the piston out completley, and replace it with a new one. B)
on the tpa topic, have a search around the forum for a tpa bodge, i think its been explained close to 400 times. :)
good luck :D
mat