Apple only supports OpenGL 2.1 (plus extensions). The Fifth Edition of the book only covers OpenGL 3. GLSL has changed a great deal since 2.1 and this book is very incompatible with any released version of OS X as of this writing.
If you want to write OpenGL that is compatible with a Mac, get the Fourth Edition of the book.
If you are a contractor, structure your agreement such that maintenance and support requests outside of the SPECIFICALLY DEFINED scope of work are charged on a per incident cost.
There is a long history (and associated case law) for per-incident support billing. Get behind that.
If you are an employee, get your employment expectations in writing. Do this before you are required to meet those expectations, and ideally in the context of discussing your compensation.
Chasing an employer for unexpected overtime fees sucks for everybody and gives you a bad reputation. Be proactive about compensation.
The hardest part of climbing the ladder of success is getting through the crowd at the bottom.