1. Have you ever calculated that you'd need four network engineers to pull and install the cable, only to discover that you only have two network engineers for your project? (How come 'have' is not 'had' Or should it be 'have'? If so, could you show me how is it 'have' ?)
A careful writer would use 'had'. Simplified:
'Have you ever calculated... that you would need four engineers, but discovered that you only had two engineers?'