This was a mistake. And every time you "reassure him", you're teaching him that you will come when he whines. My strong advice is to put the crate where you want it to be and let him whine, cry, howl, whatever until he realizes that you're not coming to "reassure him". Ignore it. He will get the idea and then go to sleep. Every time you go to him, you're making a mistake.Five minutes later, more whining. He would fall asleep and wake up every ten minutes to find me. I had to get out of bed to reassure him b/c he'd start howling/whimpering.
As regards leaving the house, once he gets used to the idea that you aren't coming because he whined, he will calm down in his crate. Since you came to him when he whined in the night, he thinks whining brings you back, so of course he's going to whine when you leave. Just start ignoring the whining. Don't go to him or even look at him or let him out of the crate when he's whining. What you need to teach him is that whining doesn't do any good, so it's wasted effort. Then he will stop.