What are the risks involved in having a vertical cliteral hood piercing?

Maybe serious. The last person i saw with this had osteomyelititis. She had infection which destroyed several spines which collapsed. The pain was intense & she is now several inches shorter. She spent a year in hospital & nursing home on IV antibiotics. I saw her because she had a severe reaction to an antibiotic. Find some other way to express yourself.
Many. A number of potential problems can occur when women have genital (to include clitoral) piercings. Jewelry worn through the piercings may cause condoms to break during sexual intercourse ; for diaphragms to become displaced. There is risk of bleeding, allergic reactions (especially with any nickel content in jewelry), scarring (to include keloids) and infections.
Yes! The other possibility, when you are considering this, is loss of sensation. Keloiding is overproduction of scar tissue. Scar tissue has no feeling, right? Think about that...