How are these used in conjunction with the Fifth and Fourteenth Amendments in protecting individual rights?
I would say that the fifth and fourteenth amendments are critical in speaking for those who lack a consensus based voice. The framers were rather brilliant in ensuring that the rights of the accused are included in the original Bill of Rights. They understood quite perceptively that the rights of all individuals are fairly worthless if the worst of society are not afforded the same entitlements. When one group's rights are sacrificed, the rest are not that far behind. Slippery slope arguments not withstanding, the fifth amendment's protection of the accused served as a benchmark of fulfilling the promise of the new nation. Such an establishment of due process was extended in the 14th amendment's protection for people of color, individuals who had been excluded from the Constitution at the time of framing. In recognition of these individual's rights and the overall notion of speaking for those who were not originally spoken, the 14th amendment's guarantee continues the fulfillment of the promise of a nation.
I think that you are probably talking about the other amendments in the Bill of Rights when you say "these."
The 5th and 14th Amendments prevent Congress and the states, respectively, from infringing on people's rights to life, liberty, and property without the "due process of law." What that has been taken to mean is that the government cannot take your liberty without convicting you of a crime. The courts have, for about 100 years, been using the 14th Amendment to say that the states must also protect the rights mentioned in the Bill of Rights. They have said that those rights are part of a person's "liberty."