Firearms and Abortion

Even though abortion nor privacy are ever mentioned in the Constitution, why do some people so liberally view the Constitution that they can see:

• the right to abortion
• an infringement of rights for requiring a waiting period
• abortion acceptable for all ages
• late-term abortions are acceptable

But at the same time, strictly view the Constitution's second amendment and believe:

• people should not own firearms
• waiting periods are required
• only adults can purchase firearms or ammunition
• all owners of firearms should register every firearm
• a waiting period between purchases is necessary
• only the government can possess firearms (even though the National Guard wasn't formed until 1903).
  

Rights and Restrictions

The U.S. Constitution lists several rights that Americans have.  These might include freedom of religion, speech, assembly, and privacy.  Privacy is not directly mentioned, but it is generally interpreted that way from several of the items in the Bill of Rights.  These written rights are defended by all Americans...

...until something happens and then some restrictions are added.  You can't yell 'Fire' in a crowded room.  You really don't have the right of privacy if you are a celebrity.  You can't own a firearm until you are an adult.  Even the Constitution itself mentions libel and slander while also mentioning the freedom of speech and press.  The end result is that we have some restrictions and responsibilities on each of our rights.

So I am wondering what are the rights, restrictions, and responsibilities of some of our 'rights' that are not specifically written into the Constitution.  In particular, what are the boundaries to our 'right' to a quality education, our 'right' to quality health care, and our 'right' to an abortion?