1) It depends how your tama is going to have the baby
-via connection with another tama - from 24 hours after becomming an adult
-via matchmaker - after your tama turns 7 years old
These aren't hard and fast rules, just the average normal tama cycle
2) The twins are widely considered to be an unconfirmed rumour that surfaces every so often, I've never experienced it but there are many many topics about it so you'd be more likely to find your answer by reading those :furawatchi: