Yes, we provide a 90 days warranty on all our repairs except physical Damage / Liquid Damage.
Yes, we carry out a complete checking of your MacBook and will keep you updated for any other faults found before going for the repair.
It is not essential, but we strongly advise always backing up your data, music and pictures before sending your laptop away for ANY repair.
No, that is not necessary since we keep all power supply units in stock.