1. Youself, it just want to determine the purpose why you apply for ITIN.
2. You will not get ITIN immediately. It takes about 3 to 5 months. IRS will send it to you via regular mail. If you have not received for 6 months. Call IRS.
3. Read IRS Pub 519 regarding dual status. It's difficult to determine just based on brief info you provided here.
4. In the line where it says charitable contribution if you itemize your deduction. If you use standard deduction, you can't claim it.