Scorpions are vermin, not animals, so, no, you cannot throw several scorpions at an enemy using animal friendship to control them.
There is nothing wrong with a druid having some viper snakes as pets since they are animals so long as you observe the guidelines and rules for animal friendship.
Some things to remember:
While on your person, these snakes aren't actually part of you so they don't get the benefit of any personal range spell effects nor are they affected by touch range spells that target you. So, for example, if you cast endure elements (fire) on yourself and get nailed by a fireball, the snakes do not benefit from your fire resistance unless you cast it on them too. Another example: tree stride lets you move from tree to tree, but your pet snakes get left behind.
They don't become part of you when you use wild shape. So if you turned into an eagle and tried to fly away, you would leave your snakes behind. Putting them in a sack doesn't help; the snakes do not transform like the sack does; snakes are animal companions, not equipment.
They have no reach so they don't get an attack of opportunity until your opponent attempts to grapple you and not before then.