Yes. People on meth tend to pick on their skin that can provide a portal of entry for bacteria that infect hair follicles and result in boils.
IV use. Iv drug use can absolutely increase the risk of skin infections. All they need is a break in the skin. Dirty needles can also introduce infection into the blood stream which can easily be deadly.
Yes. It depends on the methamphetamine is being used. You can develop some very severe infectious with unsterile injections of material.
Impaired immunity. Drug use can damage all of your body's systems, including impairing your immune system. As a result, this can make it easier for you to get a host of infections. If you are using drugs iv, then you increase your chance of infection. In addition, the use of unclean needles and other unsterile IV techniques can cuase skin infections.