Yes. Keloids are caused by skin injury in susceptible people. While piercing is one of the most common causes, tattoos (due the injury caused by the needle) are also common. In addition, some people can have excessive reactions to certain tattoo pigments which can lead to scarring.
Not safe. Tattooing can cause keloids. Avoid! Keloids & hypertrophic scars are basically treated the same initially: silicone tape/gel (myscaraway, from walgreens/online). If these don't help, see your dr for steroid/bleomyvin injections, or external electron-beam radiotherapy. Do not let anyone cut it out if keloid confirmed, it will simply grow larger!
Yes. Any injury to the skin, even minor ones, can cause keloids in someone prone to their formation. Piercings are a common area where keloids are found. I always check ear piercings before surgery to see how my patients heal. If a keloid can form from a single needle puncture, imagine what can happen with tattoos. Tattoos require hundreds of needle punctures (though not quite as deep.).
Yes. Depending on the location of the tatto ie should or chest and the tendency of your skin to get keloids it is possible.
Yes. If you are typically form keloids with scars than it may occur here as well. If not it would not be likely. The treatment will break the skin and while it not all heals without long term issue, keloid is a risk of the treatment.
Possibly. In the early stages the risk is very low to develop a keloid. In the later stages when the ink load is very low and the fluence or laser energy high there is more injury to the dermis which could possibly cause keloid scar formation I base my own patients on the severity of keloids formed if they for them with minor injury or ear piercing then no laser tattoo removal.