Answer to: Repair front brakeYou will also have to collapse the caliper pistons. In other words push the pistons back into the caliper. If you don't do this you won't be able to get the new pads over the rotor.
Answer to: car randomly wont crank. alternator, starter and battery goodThere are a number of reasons this could happen. there are neutral safety switches in both the automatic and stick shift versions of most vehicles. There is also a starter relay in the fuse box on some vehicles. check the battery cables to see if they are clean. I have seen people clean the outside of the cables but there needs to be a good connection between the post and cable or side terminal. they need to be removed to be cleaned. You say the starter is good but a bad starter solenoid could cause this problem. If this is the case I recommend replacing the whole starter. Ford cars have a separate solenoid and can be replaced separately.