Does having a tan help protect me against getting skin cancer (i.E., can the use of suntan lotion be reduced as I become more tan?)?

Tan. Tanning is equated with sun damage. The minimal " spf" afforded by a tan so to speak is not sufficient to protect one from the ultraviolet radiation that leads to skin cancers. Always use a broad spectrum sunscreen and reapply frequently.
No! Pigment does have a slightly protective effect from sun damage, but you should always wear a zinc or titanium based sunscreen of at least spf 30, regardless of how tan you are. Skin cancer is on the rise, and every exposure is a potential source.
No help here. The sun tan lotions simply give you a tan like appearance but will not protect your skin from the sun damage which leads to skin cancer. The only protectors are sun screens which contain chemicals which block the sun rays. The best way to protect from skin cancer is to stay out of sun, but if you have to go out in the sun for any reasons , use a good sunscreen and apply it every 2 hours.