Find the dot product $v*w$ and the angle between $v$ and $w.$

$v=2i-4j+k,w=i+2j+3k$

$v*w=-3$

$($Simplify your answer. Type an exact value, using radicals as needed.$)$

The angle between $v$ and $w$ is $=$

$($Do not round until the final answer. Then round to the nearest tenth as needed.$)$