回複：申請H1B需等H4 approved?

1. Yes, inclue a copy of H4 application receipt in your H1B application. Premium processing takes only half month.
2. You need to withdraw the H4 after your H1 is approved. Otherwise, if your H4 is approved after your H1 approval, you have to either refile H1 again or travel abroad and come back on H1 visa to regain your H1 status.
3. It is a bit gray. You can start your new job after receiving new receipt according to AC21. However CIS never come up with the final regulation on a situration like you. On the safe side, wait until the approval notice.