My name is XXXXX XXXXX I'd be happy to answer your questions today.
For a bill to become a law, it must pass both Senate and the House of Representatives
by a majority vote, and the President signs it. if the President vetoes the bill, or takes no action, then it goes back to Congress, and they have the option to override the President by passing it again, with a 2/3 majority vote. A bill always originates in the Legislature - the President can encourage people to introduce certain bills, and can publicly give his support, but he can't just unilaterally create a bill and make it the law. An Act is simply what the bill becomes when it becomes law.
What the President CAN issue is an executive order, which I believe it what you're talking about. The President is Commander in Chief of the military, so he's allowed to make decisions related to military operations without Congress.
I don't believe Romney thinks that he can enter office and immediately start passing any law he likes. That would imply that he doesn't have any understanding of how the separation of powers works, and he was simply governor for too long for me to think that's possible. Obama delayed a decision on the Key Stone project until 2013, so I believe that what Romney meant is that, since the project is in limbo awaiting executive approval, he intends to sign off on it if he is elected.