Not too many

H4 is not hard to get. You need provide:

1) copy of your I-794 form
2) Copies of your passport
3) Financial Aids (Payroll, Bank Statement)
4) Proof of marrage - marriage liencese, photos of the family.
5) Better a letter from your boss, or colleague

When your hu*****and and child go to interview, they should tell the official that they want to live with you in the states. the officer will decide to give them H4 or B1/B2 visa.