A) si, We can cook together 'if' you want.
Imparfait would be the description of a situation for example :weather, landscape, person in the past whilst passé composé are actions that suddenly happened for example, interrupting another action. Passé composé you would also use an auxiliary like either avoir or être then you would add the verb
Aujourd'hui, nous sommes vendredi. Hope this helped you! <3
