that's normal, no big deal
normal, normal again
NOT NORMAL! Before you do anything else, you need to determine how severe the rust is. From your description, it sounds like it could be pretty bad. When you say "running boards" do you mean rocker panels? The rockers are structural on a 105 Alfa.
The car may have negative value - i.e., it could cost more to fix its rust than the price of a car in better condition. Have an experienced restoration body shop assess the car before committing to purchase.
In what country was it first delivered? Perhaps they didn't have a requirement for side markers back in 1972
From one photo it is impossible to assess its appearance. The grille, bumper, and front fenders look OK. But I can't comment on the rest of the body, the interior, underhood, undercarriage, ......