You'll need a proper wind back tool, I'd post a link but I'm not allowed! Do a search for 'caliper wind back tool', I got one from tooled-up dot com.
Hopefully you wont need new pins, but make sure tyou take them all out and give the pins+holes a damn good clean. If you spot any corrosion/pitting they'll need replacing. Oh and the rear seals come with a sachet of special grease, you have to leave all the seals submerged in it for a few hours before you begin. this is because the rear pistons spin in the caliper when the handbrake is applied, so theyt need special lube to prevent them tearing. Front seals just use boggo brake fluid.
Part numbers:
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443 698 470 - front/rear caliper slider repair kit - 7.92+VAT x4 (1 per caliper)
contains:
2x boots
grease
2x Caliper bolts
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8D0 698 671 - rear caliper cylinder seals - 12.28+VAT x1 (1 kit contains enough for 2 calipers)
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431 698 471 B - front caliper cylinder seals - 8.16+VAT x2 (1 kit contains enough for 1 caliper)
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N 907 085 04 - front carrier bolt x4
N 019 912 3 - rear carrier bolt x4