audit procedures is general term its meaning will be depend on circumstances
it generally means observation / inspections / inquiry / recomputation / reperformance / external confirmation / etc
it can also mean test of controls / substantive procedures
it can simply mean follow particular SA

meaning of implication also depends on circumstances
it generally mean changing risk levels / changing trust levels / thinking about more evidence / thinking about resignation 

nature means observation / inspections / inquiry / recomputation / reperformance / external confirmation / etc
timing means whether weekly / monthly / quarterly / annually