Can I use PostLab if I haven used the other stages of LabWrite?
Yes. PostLab is a guide for writing your lab report, and you may use it independently of the other stages of LabWrite. When completing the Introduction of your lab report, make sure that you select the choice for users who have not completed the PreLab. Also, make sure that you follow the usual instructions for selecting a type of lab and a mode for writing your lab report as explained above in question #2.