No. Your genes are a very small part of your cell structure. They are involved in the process that allows you to grow by being a part of the cell division process by which each cell reproduces itself in a controlled manner. In certain circumstances, and no one is really sure why in my opinion, the cell reproduction process is interupted and your cells begin to reproduce in an uncontrolled manner. This can lead to a tumour that may or may not be cancerous. If it is found to be cancerous, then any one of those cancerous cell that contain the aberant genetic material can spread and deliver cancer to another part of your body.

No. All genetic material is located in the nucleus in each cell, and each cell in the body has the entire genome i.e. all the genetic material. Cancer is caused when cell cycle regulation machinary fails. This could be due to a mutation(change in DNA) caused by chemicals, viruses etc. Various genes such as tumor suppressor genes and protooncogenes become abnormal, which leads to loss in control of cell division, resulting in cancer.

Actually, you are probably thinking of "retrotransposons". These are small sections of DNA which simply copy themselves, over and over and over; they are not "functional genes" which code for proteins, the only thing they code for is more of themselves. They are essentially parasites, parasitic sequences which use our DNA replication mechanisms to continue their existance. These do make "extra" copies of themselves which can re-insert into the genome in almost any place. They are fantastically successful at it, too; over 40% of our genome is composed of these transposon sequences. Because they tend to re-insert into DNA where the DNA is partially unwound to allow active gene transcription, sometimes they do insert actually *in* a gene or regulatory sequence, and disrupt the function of the gene. Sometimes this creates a functional mutation; it's another source of variation in our genome. Many times, though, they disrupt gene function in a bad way, and yes, it is possible then that it could contribute to cancer. There is nothing that you can do about it, though. This is simply the way our genomes tick over, and have done for hundreds of thousands of generations.