2) How can one perform a self-check for the symptoms of skin cancer? How often should it be done? What should one look out for?
Performing a self-check for the signs and symptoms of skin cancer is imperative for someone at high risk for skin cancer. For most of us, once a year is the minimum recommendation.  For someone with a higher risk for developing skin cancer,  for example, a personal history of melanoma, doing a self check should be every 1-3 months as recommended by your dermatologist. The more feared form of skin cancer is melanoma which can often be detected by a self-skin exam  Firstly, good lighting is important.  You will need a fixed mirror as well as a handheld mirror. Think of dividing the body into 12 parts.  Scalp, face, neck, chest back abdomen, right arm, left arm, right leg, left leg, buttocks and genitalia.  The hardest areas to examine are the back buttocks as well as back of the legs. (my older patients get the joke that  you need a mirror unless you are Linda Blair)  Don’t forget to check between your toes and bottom of your feet (soles)   Melanoma is equal in incidence in the front and back, it can more thicker and more  deadly on the back due to the delay in discovering it.  (i wrote about this in the year 2000 in Archives of Dermatology,  reference available)   Sitting in a bathroom to examine the more difficult parts of the body is can be helpful .
3) In general, what are some reasons, one should see a doctor re: possibly having skin cancer? Should you see a dermatologist, an oncologist or another expert?
There is some credence to the ugly duckling sign,  that is,  observing a spot that is different in appearance from the others or that changes, bleeds or itches should results in a visit to your dermatologist.  We often use the ABCD rules, that is asymmetry, border irregularity  (think coast of Norway)  color variation or jet black, and diameter greater or equal to 6 mm  (size of a pencil eraser). Another common reason patients give is,  “i have this pimple for 3 months that won’t go away.”   A dermatologist spends a 3 year residency specializing in the diagnosis and treatment of skin cancer.  More than any other specialty, we are trained in judging the appearance (morphology) of spots on the skin and also determining what does not require treatment. We often use magnification and special handheld equipment like a dermatoscope and digital photography to follow the appearance of a suspicious lesion.
4) Generally speaking, what are the treatment options for skin cancer?
There are many options for skin cancer including surgical and non-surgical options.  Most skin cancers are typically removed (excised) under local anesthesia in the doctors office. For some small skin cancers, particularly on the trunk, topical creams like imiquimod and 5-flourouracil cream can be options.  Radiation therapy is another option, particularly for an elderly patient who may have a hard time with surgery. Another less invasive option for basal cell and squamous cell skin cancer is electro-dessication and curettage, photodynamic therapy using lasers.