According to
http://www.cic.gc.ca/english/immigrate/skilled/funds.asp you don't need to show funds if you have employment. Show them your contract.
The principal applicant needs to land before or with the other applicants but after they all land, there is no primary applicant anymore and each person becomes responsible for keeping their residency requirements or lose their PR.
The only thing different for a child is that if one of the parents has fulfilled the 3 in 4 years requirement to apply for citizenship, they can apply for citizenship also for their minor child who is a PR, even though the child has not stayed 3 in 4 years.