Louisiana Purchase allowed for more farm land but was not in the president's power: Jefferson was a strict Constitutionalist meaning if it wasn't it the Constitution then he couldn't do it. Purchasing land was not addressed in teh Constitution and therefore he thought he shouldn't. However, Jefferson supported farming and the land would open up that industry. Ultimately he was convinced it fell under his power to create treaties.
The Embargo Act was used against Britain because they were firing on US ships during the Napoleonic Wars: This act hurt US shipping and trade because Britain was a main trading part. Also they stopped buying from the US stopping the US economy.