Hatching: you need a very hot area. Use standing torches in a circle (10 to 15). Or build a room with a lot of air conditioners.
Imprinting and baby survival: Make sure you have wyvern milk. They only consume that for food when babies. You have to manually feed it to them until they are juvenile. It is also the only food they will ask for during care. Also set the follow behavior to lowest and disable wandering in case they wanna walk.
Wyvern milk can be obtained from knocking out a female wyvern and looting her. You get 5 milk. Doesn't respawn on same female.
Alpha Wyverns can be killed and looted for 50 milk.
Milk can be stored in preserve bins but not fridges.
Wyverns have 3 attacks. 3rd attack changes from flight to ground. Primary=bite, secondary=breath, tertiary(flight)=pick up creature, tertiary(land)=wing flap that pushes back enemies and knocks down trees(collects thatch more than wood)
No saddle needed. Friends can stand on back. Dismount doesn't throw you.