The word "would" comes from the word "will". This is like an "if clause". It is not certain, and depends on someone's decision. You could not say it "will be" easier, because there is no certainty that she will quit her job. It depends on what she decides. If she quits her job, it will be easier on her, and it would be easier, less stressful, if she would quit her job.

It means "will be" when you're giving an example. If you do something, it will be better to do it this way, but we say, "If you were to do something, it would be better to do it this way.". It means I know the outcome and in time you will see that I am right. (or maybe you'd find them to be wrong, then they'd say, "I would never have thought that" - "would" is "will in the future".) That seems confusing for me, tell me if you understand it.

future tense. in the future when she quits her job, it's not going to be stressful

In this sentence would is used for an unreal case,normally we use it for unreal situations. ''If you quit your job,it would be better for the kids.''(she have not quit her job yet)

First of all, it's spelled as "sentenCe." Would is used like how you use will. The difference is when a person uses will, he's sure he will be able to do it. Would can be used in different situations.. This might help. http://www.englishclub.com/grammar/verbs-modal-would.htm