For question #3:
Please check your Form I-797 approval notice for H-1B, if it comes with I-94 (on the bottom of the notice), then you don't need to go back to apply for H-1B visa. In this situation, you need to send your original approval notice with a set of attorney certified copy of H-1B (including employer's letter and your recent paycheck stubs) to your wife. They need to take these documents with marraige certificate (for your wife) and birth certificate (for your kid) for visa interview.
If the approval notice does not have I-94, it means the CIS requests you applying for a visa at U.S. consulate abroad (usually in your home country).
Please check your Form I-797 approval notice for H-1B, if it comes with I-94 (on the bottom of the notice), then you don't need to go back to apply for H-1B visa. In this situation, you need to send your original approval notice with a set of attorney certified copy of H-1B (including employer's letter and your recent paycheck stubs) to your wife. They need to take these documents with marraige certificate (for your wife) and birth certificate (for your kid) for visa interview.
If the approval notice does not have I-94, it means the CIS requests you applying for a visa at U.S. consulate abroad (usually in your home country).