Stye in the lids is caused by bacterial infection of eye lashes' roots after rubbing your eyes when tired or due to eye strain. Warts are caused by viral infection. They can come one after another like acne. These are only locally infectious i.e. in the surrounding tissues.
First thing is to make sure he does not need glasses and wear them if he does. Second is to never rub eyes especially with dirty hands. Styes sometimes need operation but they can disappear on their own if left long enough. Initially local antibiotic cream and hot fomentation will be helpful.