Set up workflow procedure using Trello, Everhour & Google Drive/Dropbox that integrates with Xero

We wanted to use workflow max to integrate with xero, but weren't happy with the UI. So we went to trello, which we love and are in the process of linking trello and everhour. But something's missing, so we need someone with a bird's eye view to come and help us make our system tick. We will move to workflow max when things improve, but meanwhile perhaps we can improvise with our original online WIP on 'google drive'? We're looking for the best solutions for: - loading a new job into our system - assigning jobs and production coordination (scheduling) - tracking hours spent on jobs and invoicing accurately - budget management and maintaining profitability - simple and easy to share briefs - to do lists/task lists for team members ...and all other components of production our creative organisation handles including: - Marketing & Communications Strategy - Marketing Management and Coordination - Creative for all forms of marketing & advertising - Online development (websites, blogs etc) - Social media management and creative - SEO, adwords and retargetting.