If you get job right away, this is a possibility. Consider the fact that as a freshman, it will take some time to get used to the surrounding and getting the job.

2.       Summer on-campus work- 3k

Again, you need to be really proactive for this. Jobs are less during summer than in other semester. Additional you are competing with Americans (students who will stay for summer classes) for the summer jobs.

3.       Parents contribution-2k ( my parents can pay more)

Don't depend on your parents after startup/initial year. Try filing out economic hardship condition work permit (gives you piece of mind and flexibility to work off campus during summer for 40 hrs - would not advise strongly but just keep in mind)

4.       Live off campus- save 2k
This is a good idea and a must.
Also consider variables here. DON'T WASTE YOU HARD EARNED MONEY IN DRINKING BEERS ON FRIDAY NIGHTS OR WEEKEND! Try to choose good roommate!

 How practical are my assumptions?
Pretty good. Always consider ups and downs in life. Save some for unseen times. You should be all fine.