The US-Canada Free Trade Agreement, passed by Congress Monday, was signed by President Reagan and Canadian Prime Minister Brian Mulroney Jan 2. Canadian approval is on hold, pending parliamentary elections expected this fall. The pact provides for: Elimination of all tariffs between the two nations within the next 10 years. Removal of quotas and other restrictions on virtually all existing imports and exports. Removal of the current Canadian embargo on imports of used motor vehicles and aircraft. Investments would be granted national treatment in each country, with some existing restrictions retained. Canada would be able to continue protecting its ``cultural'' industries, such as the news media and book publishing. Mechanism to standardize American and Canadian agricultural rules and regulations. Greater access for US farm products to the Canadian market. Minimum import quotas on Canadian poultry and eggs would be increased. Lifting of barriers to the sale of US-produced wine and distilled spirits in Canada. Nondiscriminatory access for the US to Canadian energy supplies. Canada would gain limited access to oil from Alaska's North Slope. Rules under which laws dealing with subsidies and the ``dumping'' of cheap foreign merchandise would remain, but duty decisions may be appealed to panels of Canadian and American experts. Elimination of many restrictions that require government agencies to buy products made only within their respective country. Equal treatment of citizens of each country who provide services in the other. Rules that would be set up to prevent products from third countries entering Canada or the US through the other without being subject to duty.