Item 1:  Bumpkeys are not master keys, they work on an entirely different principle.  Master Keys are often used in public buildings so emergency responders (Firefighters) have access to the entire building in the event of an emergency.  This master key is kept in a knox box and only the local Fire Department has access to it.

 

Item 2:  Often more expensive locks have more convenience or are more stylish.  Spending more on the lock is not always the correct answer for your security situation.  For example, if you have a rather flimsy door frame or door, a high security lock won't keep the door from being kicked in.

 

Item 3:  As already stated, these locks will not increase security, but they will increase conveneincem which will increase use.  If your friends and family can just enter a code or scan theur fingerprint to get in, you are more likely to keep your door locked.

 

Item 4:  I had to add this item.  I often get this question when someone has lost the keys to their car or truck.  We use a variety of techniques to replace lost keys, none of them include making a mold of the lock.  Some do include making measurements of the lock using special tools that look like keys.