1 - Here is a good overview for distinguishing between standards and curriculum and it explores various elements included - http://www.excelined.org/2013/06/03/common-core-fact-of-the-day-standards-v-curriculum/
2 - What should be included in the curriculum is up for debate. I think a good argument can be made that it must be a coherent roadmap for guiding students to develop a competent foundation of knowledge and skills that reflect the enduring concepts and ideas within the particular discipline.
3 - Who should design the curriculum? Again, this is up for debate. Having been a part of multiple statewide efforts to revamp standards (done before curriculum is outlined as it is based off those standards) I can say that many states feel that curricula ought to be designed by carefully chosen experts who represent stakeholders of interest in the discipline (generally, we're talking about teachers and honestly many of them are downright disrespectful to comments from parents, which I found a bit distasteful even if they aren't always informed).
Here is a nice link to get you started on this - it's an older one, but a good one to review - LINK: http://www.ascd.org/ASCD/pdf/journals/jcs/jcs_1987summer_portelli.pdf
You shall find many persons with the answers for your questions at Indiana University Blooming.
While defining the objectives all the program, curriculum shall be worked out in all the aspects of theory and practicals.
Later, details of the individual subjects shall be described and the resulting syllabus shall be passed in the Board of Studies and Academic council of the University. One shall find teachers of the same university, other university, experts from industry, representatives of Government for the committee to frame the curriculum, syllabus. This is a long process.
Dear Samira, In my opinion curriculum is a teaching process plan for developing skills, competences and knowledge as well.
It must be deesigned by the given teachers (lecturers) who teach the subject because it should contain as well as aims, chriteria, topics, sources and methods for teaching and evaluation.
We generally use core-curriculum at universities but there are many types of these documents depending on the claims.
My instant response to this is that curriculum is 'everything that happens' which is a bit of a cliche I know but it sums up so much. I don't agree that curriculum is only designed by teachers (with due respect Agnes) because I am working in early childhood we encourage our teacher education students to see curriculum as something that is dynamic and is co-designed with the children. This could, for example, be the types of questions and projects the children are interested in investigating further. The educator brings an intentional focus to these inquiries based on their pedagogical content knowledge. Some further reading on this can be found by looking at terms such as 'emergent curriculum' (Jones and Nimmo)