It sounds like a "fear stage". I do not totally agree w/ ramanth. Yes, remain calm so Nebo can sense that but do not talk in baby voices & praising as it is just praising him for acting nervous & will probably make it worse. Just a simple short pat & "its ok". When he is calm then praise, praise, praise! You can try to destract him with a sit command or down command etc... I would enroll him in another obedience class & try to get him out as often as possible. The more socialization the better. I would not worry about the vaccume thing as it is fairly normal for dogs to act frightened by it.

He should reach his adult height at around 9-12 months. Then he will start to fill out for up to a year after. By 1 1/2 -2 years they are fully grown. But they grow slightly slower as they get older and a husky is not too big of a dog ussually around 50-60 lbs.