There are a couple of Nepali students with assistantship at the University of Akron, Ohio. If you are electronics major, then you probably know some of them. Please include that university in your list.

One important note: Universities usually select international students for scholarship or assistantship based on: 1) Grades of your undergraduate degree 2) TOEFL test score 3) GRE score and 4) Recommendations of your professors (or supervisor if you have already been working). They may overlook other scores only if you have an EXTRAORDINARY score in GRE.

Most top universities have application submission date 9 months ahead of fall quarter because they need to select applicants from all over the world. But remember, it is often the case that you may submit some of the scores such as GRE at later date, it is not necessary to have them with the application. I hope I answered some of your questions. Wish you good luck.