The way I usually try to resolve dilemmas like this one is to simply do a Google search using the term in question. Tonight when I searched "pizzeria", I got 4,840,000 hits. When I searched "pizzaria", I got 758,000 hits, plus a query on whether I meant "pizzeria". It seems logical that pizzeria would get top billing since the term pizzeria apparently derives from the Italian word "pizze" for pizza (plural form). Pizzaria is most likely derived from "pizza", which is the American term for what we refer to as pizza. Noteworthy also is that DiFara's, Patsy's, Grimaldi's, Bianco (Chris in Phoenix), Pepe's, Lombardi's, Totonno's, Uno's, Gino's East, Giordano's, and Malnati's all use Pizzeria in their names. That tells me that they must know what they are doing.
As for "pizzaiolo", I refer you to our Glossary for our best definition, at http://www.pizzamaking.com/pizza_glossary.html
What I can't tell you about the term "pizzaiolo" is how to pronounce it.