I don't know what you mean by "override" - a power of attorney is a completely different document from a will. A power of attorney generally gives Person B authority to handle Person A's legal and financial affairs while Person A is alive but incapacitated in some way. Upon the death of Person A, the power of attorney becomes null and void and no longer gives Person B any authority over Person A's assets or affairs. A will is a document in which Person A can name who they want to be the executor of their estate *after they're dead* and directs the disposition of their assets *after they're dead*. Until Person A dies, their will has no legal effect and is just a piece of paper. There is no overlap between a power of attorney and a will so there is no way one can "override" the other.
There is no difference between an attorney or lawyer - one and the same. They are sometimes referred to as Esquire as well. Most of the people defense attorneys defend are probably guilty - if you don't like that then join the prosecutor's office. Low man on the totem pole in a law firm gets the types of cases no one else wants. Of course, there are attorneys who specialize in other fields e.g. tax attorneys, corporate attorneys, civil litigation, etc.
Some judges are elected. Federal judges are appointed for life so it's all in who you know and the reputation you've earned. Many federal judges contribute to their political party and are rewarded if their candidate wins. Some federal judges are magistrates which means that theirs is not a political appointment and they aren't guaranteed the job for life.