They are probably less likely to consume large amounts of prepackaged desserts, sodas and snack foods than their "English" neighbors, but that varies from community to community.
Cigarettes though.. the youth still love them.
However, your second point is not applicable. The Amish have a culinary tradition of their own that stems from 18th C German cooking adapted to American ingredients. Because they strictly limit their exposure to technology changes, they do more manual labor than is common for their neighbors, but this isn't correlated with a lack of desire for good (tasty, appetizing, visually appealing) food. If you tour Pennsylvania, Ohio and Indiana, you'll discover Amish foods and handmade goods being sold everywhere.
How does that work?
caramel
cream
dough
powder
crystal grain
icing
...
I'm sure it happens, but it would be extremely difficult to find people who have similar diets as the Amish, as you'd have to grow your own food and butcher your own animals to achieve a similar level of diet.
Presumable the p-value for normal Amish 7% vs. rest-of-US 8% is not significant in the numbers they studied, but the 7% vs. 0% was.
My fried growing up was from Pennsylvania and would bring back massive amounts of candy from Amish country. Whenever I drive to Florida I see many road side stores touting “Amish made candy”.
The answer is yes they eat the candy they make as well.
Yeah, sugar is the work of the devil. But it's the amount Americans ingest in many other forms that create obesity, type 2 diabetes, etc.
My dad used to buy chocolate chip cookies and gobs[1] from the Amish at the farmer's market. They were huge, and good but definitely not healthy :)