CRM Workflow Plugin

Good afternoon all, I have a project that I’m working on that I require help with, the client has asked for a workflow system to be added to an existing CRM I’ll be doing the other features (these two things are not my strong point as I am a developer myself). The workflow should as the following: Admin/Manager is able to create a process/steps that leads to the next step, the backend (admin) should have functions such as “send email”, “task user”, “change status”, “send invoice”, “start subscription” etc which the admin/manager can select. (The CRM has these features already so they just need tied in) The workflow should also have a feature that can delay next step for X amount of days at X time, again these will be in the backend. It should also have a feature that the workflow will “pause” until the next task is actioned or if selected the workflow can action a task if no time or days etc are selected and continue until it needs to stop. Another feature that this needs is to “start workflow” which should show the workflows created, this meaning when workflow one is done, it can start a workflow 2 which could perhaps loop forever etc. When in the customers details, an area should appear with a workflow selection and when selected it will run that workflow for that client. (if you are familiar with FLG 360 you’ll know what I’m meaning) It’s not a big job for someone with experience, you will need to have PHP and MySQL experience for this job, I will need examples of something similar you have done. This project will be starting this week.