Is the us a democracy with a government and laws based on the constitution or is the us a democracy with a government and laws made by the president?

neither. The US is NOT a Democracy, but a representative Republic. In a Democracy the minority is not protected from the majority. This is often illustrated with the metaphor that a democracy is two wolves and a sheep voting on what's for dinner. The laws in the US are created by the congress, approved by the President, and validated to be constitutional by the Supreme Court in a delicate system of checks and balances.