H-1 一定要 file 1040 吗？

1)以前F1一直file 1040-NR for tax return? 今年H-1一定要 file 1040 吗？
2)2003 年一直用OPT,是否还能享受 $5000 tax exemption based on China-USA treaty with 1042 form.
3)My company HR will not provide 1042 form for me, any suggestion where I can get this form? Thanks.