To answer your first question: No. The results of those experiments are not used. In addition to the ethical concerns, most of the experiments simply had no scientific value, and even the oft pointed to hypothermia experiments have been shown to have very serious flaws which would undermine even an "ethic-blind" approach.

We have a FAQ section on the Nazi Human Experimentation with comments that go into more detail.

As for your second question about ethics: That is a very very very firm no. Even aside from the egregious offenses committed by the Nazis, multiple organizations who examine, debate, and set ethical policy and regulation have ruled that prisoners as subjects must be given special consideration, at the very least.

The Nuremberg Code that emerged from the Nazi Doctors' trial does not coincidentally start by saying "The voluntary consent of the human subject is absolutely essential." Voluntary consent, and the freedom to terminate that consent, has become a core tenet of human subjects research in no small part because of the Nazi experiments. An incarcerated person, by the very nature of their condition, has diminished autonomy. Moreover, they are in a situation were even small promises of reward have the potential to be highly coercive in their decision to participate and/or stay in a study.

As a non-Nazi example of this, when the US Public Health Service was trying to find out what caused and cured pellegra in the early 20th century, they conducted an experiment on prisoners. For context, pellegra is caused by niacin deficiency, whose symptoms start mildly enough, but can quickly progress to dementia and then to death. In 1915, however, none of this was known. Although a dietary cause was suspected. Still, the notion that pellgra might be infectious or that the investigators might not be able to cure the illness once they induced it, was an absolute possibility.

In exchange for taking part in the experiment, the prisoners were offered pardons from the governor. That may seem a fair trade, but again keep in mind that they were being asked to willingly submit themselves to getting a disease whose etiology and cure was at that time unknown, and which could potentially kill them. The proffered reward was a release from incarceration. The prisoners were literally asked to risk their lives for their freedom.

Such exchanges are incredibly coercive, and thus why modern research on prisoners does not permit such a trade. In the United States, the Common Rule for research using human subjecst was developed after the atrocities of the Tuskegee Experiments were unveiled to the public. The regulations specifically recognize prisoners as a protected class, with restrictions on what kind of research can be carried out in prisons/jails and specific items for ethics boards to consider with regards to coercion.

None of this was in place in the Nazi camps, and those subjected to the experiments did not even have the option -- like the USPHS subjects -- of volunteering. They were subjected to experiments against their will, whose outcomes were known, and even desired, to be deadly. Again, it is not a coincedence that the Nuremberg Code specifically notes that experiments whose outcome is suspected to be death may not be conducted, unless the experimenters themselves take part. Moreover, many of these "experiments" were nothing more than sadistic torture carried out under the guise of out-dated even at the time pseudoscience. Unethical and unusable all the way through.