Sales Quote, to creating a work order to AR invoicing

I am unsure as to which modules I would need to use or start looking into if I am trying to do the following:

1. Raise/generate a sales quote for a customer to perform services work on behalf of a customer

2. Convert the quote into work task to do the work internally

3. Track the work flow being done to know where the work is up to, with approvals along the way for work to progress from say design to development to completed

4. Invoice the client/customer for the work done ie for the amount quoted or for the amount quoted plus client approved change requests.