1 I would say that b) is the better choice.
2 The fibres are short and need to be woven together- wool is not very long on the sheep and needs to be turned into a continuous thread, as in a ball of wool.
3 With 'after that' the natural tense for me would be the simple past, implying that the traffic is moving again.
4 Not to me.
5 Fatal- has caused or will cause death- a fatal accident, a fatal illness
Deadly- capable of causing death
Mortal- what causes or caused death- a mortal wound
Student or Learner