Did you read the article up there about the origin of the list of seven nations? It is not defined in the EO, bit in a bill from 2015, under the Obama presidency.
Of course, Trump could have added Saudi to the list in his EO, and didn't, but he also didn't explicitly leave them out.
No. Only those who Trump doesn't have business deals with.
Eg Saudi Arabia get a pass, despite 15 of the 19 9/11 hijackers coming from there.