Many and varied. Many diseases can cause immune mediated vasculitis. Apart from the specific illness with tendencies to affect specific organs, the most common serious issues from all vasculitis are inflammation of renal, cerebrovascular, gastrinitestinal, and cardiac blood vessel inflammation.
Varied. Symptoms and signs can be very nonspecific - everything from a rash to kidney failure. A rheumatologist would probably be the best physician to assure the diagnosis.