While tasting beans from around the world and figuring out what I like, what type are used for Italian and French roasted beans ?
The kinds of beans used for french roast are what are called "cheap" beans. Same thing with flavored coffee. It's where roasters make money as it doesn't much matter what beans they use as long as there's enough moisture within them to not start a roaster fire. The roaster can buy lesser grades with more imperfections as those imperfections are roasted out at high temperatures (or covered with chemical flavorings).
You wouldn't roast good beans to french roast for the very reason scubadoo mentions - once you're past a Vienna (medium-dark) roast level, you stop being able to taste the terroir/aromatics of the bean origin and all you're left with is caramelization of sugars and carbony taste.
That said, some beans take to higher heat better than others. Indonesians generally take heat better than East African coffees and hold onto some of their funky earthiness at very dark roasts. Brazilians are another good choice as they're plentiful and cheap and can hold a bit of chocolate notes even at a french roast level - which is why they've historically been the backbone of traditional Italian espresso.