"After reviewing the documents, I came up with some question. Could you answer these questions?" eg "After reviewing the documents, I have the following questions. Thank you for your assistance."
"I reviewed your documents and have some questions." is very efficient. Also, this way you do not ask for permission to ask questions. You make the statement that you have questions, allowing you to immediately proceed asking. Some societies find that too direct. In the West we generally do not take offence. "I reviewed your documents and have questions, could you answer them please?" also works.