Trump v US Constitution?

Would those who are more familiar with the US Constitution please please please weigh in on which of Trump's Executive Orders and which new House Bills would actually violate the Constitution? I've seen various posts recently about a proposed House Bill to eliminate the federal income tax, the Internal Revenue Service and institute a national sales tax. Wouldn't that violate the 16th amendment which gave Congress the right to impose a federal income tax? Also, don't the majority of states have to vote "yes" for the Constitution to be amended? (I would also like to apologize to Mrs. B. Cumberbatch, my 1980's High School Civics Teacher, for not paying attention in class.)