The very fact that you have sit down and thought about how you are going to finance your undergraduate education tells me that you will do just fine. I am disappointed with Mr. Naya Nepali for discouraging someone who is well into the process of coming to the US for his undergraduate education. I disagree with him totally. You WON"T need to go to boston or texas and join a community college (like mr. naya nepali I guess). In fact the best advice I have for you is DON"T EVEN THINK ABOUT DOING THAT. I also don't agree with him that it is better to come here after getting your undergraduate degree in Nepal. I strongly recommend you to do well in your undergraduate degree here in the US, get some work experience in your field of interest, and when you feel that you will need a higher degree for furthering your career, you can do your masters/phd level study. Remember to be proactive and look for internship opportunities in your sophomore and junior years.

Regarding expenses, your estimates seem reasonable. Once you have attended college for nine months, you can apply for the work permit based on economic hardship. That's what I did. Another bright spot for you, you could also work on-campus during the winter break which is around 1 month. You can work max 40 hours per week. After accounting for Christmas holidays, you should easily be able to work full time for around 19-20 days.

As an example, here is how I financed my education:

Total yearly expense (Tuition, insurance, off-campus apartment, food. summer expenses, cell phone, personal expenses):  $9,500

Income:

On-campus employment: $4200 (worked around 15 hours/week during school and earned around $900 during winter break)

Summer employment: $12,500 (worked around 80-85 hours per week in Ocean City, a beach town in maryland which becomes a mini Nepal during summer with thousands of nepali student workers)

Important to note:

-Get that work permit after your first year and it is quite easy to find work during summer in seasonal places like Ocean City. Most students go there without a work permit and hence struggle to find jobs; if have a work permit, it is quite easy.
- As long as you have an on-campus job, don't work off-campus even if you have a work permit (unless you have an internship opportunity or work related to your field of study). Make studies your priority.
-Take whatever on-campus job you can get during your first semester; after that, try to find a job that you will be able to put on your resume when you apply for internships (eg. assisting a professor with grading and other paper works, working in a lab etc)
- Be prepared to toil hard during summer so that you can concentrate on your studies during school semesters. Classes will be tougher and will require more time commitment as you enter your junior year.
-If you do well in your first year, there might be opportunities for merit-based scholarships.

I hope the suggestions I have made based on my personal experience will be of some help to you and others that might be in a similar situation. Let me know if you have some other queries.