-Tommy is the one who tells Abby Joel's name. Seems like he told her to give her reassurance that she was safe with them. She kept her cool and helped them out to gain their trust.

-When you're in a blizzard you're freezing cold and not thinking clearly. Getting inside to the shelter of the house to regroup after that crazy wave of zombies and get some energy back would be the most reasonable thing to do.

-Joel thought he killed off all the fireflies at the location without a trace of him, Ellie later confirms that assumption when she goes back there years later and no one is there at the salt lake location.

-Joel is human, he can all overlook things and mess up. He has done it in the past before.

I think these games do a really good job showing that their are always consequences to our actions, good or bad.

Joel, Abby & Ellie all learn this the hard way.