The second quote is debated but if it was said, this is who was supposed to have said it...Yes, and in fact providing materiel to one side and not the other is generally perceived as a violation of neutrality.
The Axis would likely not have invaded the US - the supply line would have been to long.
The US learned *after* the Cold War that any efforts to actually land on or invade the United States mainland - including Alaska - were never on the table. Apparently Soviet spies had terrified the Kremlin with the fact that the US oppressed workers were heavily armed, in contrast to the elevated workers of the Soviet Union who were disarmed by their government. It seems they feared being sniped at from behind every bush, and from every urban window.
Quote: Admiral Isoroku Yamamoto "You cannot invade the mainland United States. There would be a rifle behind each blade of grass."
"I fear all we have done is awaken a sleeping giant and fill him with a terrible resolve."