i guess you'll be doing this with professionals.If yea nothing much to worry ,Normally Belly botton persing takes long time to heal than other so keep this in mind like say around months to a year.When you go for persing watch out for sterile enviroment..
Implant grade stainless steel though is expensive but most safest to use during persing.This is least likely to produce a foreign body reaction or infection in the skin. Other choices for new piercings are metals such as gold (AT LEAST 18 karat), titanium, or niobium. All of these cost more than implant grade stainless steel but are safe.