Assessment of an IT-related extended abstract
Is it customary/obligatory to publish the source code for prototypes in academic papers/abstracts?


No. Most academic articles (in IT) do not include the code. Some rarely do have a link to a link where the code and source materials can be downloaded. 


  Are scientific paper references not a requirement for an extended abstract and by some degree an indicator of the quality of the paper?


It depends on the reviewer. Some would look at the number of studies referenced to make sure that sufficient background research and literature was conducted (been through that one). Some may look closely at the quality of the references (although I haven't experienced this sort myself). Some only expect the relevant concepts too be attributed, even if only 3 or 4 items are referenced. 


  How would you assess the abstract in terms of project execution, accurracy, tracability?


If the underlying novelty is focused so as to improve performance of an existing system, then a simple line about the increase in performance metric/accuracy with respect to the state id thee art will do. Statisticians are not to find of bare accuracy. There are many other measures for This, but a simple mean+_std. dev. ought to be a better alternative. 

If the novelty lies in the application itself and not any performance measure, then this'd line would not be necessary. I'm not sure how the traceability aspect would come in an abstract. 


  How would you interpret "code exchange not necessary"?


Sorry, but that's a question for your instructor.