Can I apply for a Non-B visa with my spouse and child as dependents?

The person working will have the non-b, the spouse and child will have a non-o trailing visa,

Q. Is it possible to have two dependents (spouse and child)?

-> Basically, yes. But a child must be under 20 years old.

Q. can all three apply at the same time and how would that work?

-> Depends on where you apply for your visas.

You need to talk with your employer first about the detailed procedure with them. Some companies can let you apply for your initial visa in-country, while some of others ask you to go to the specific embassy.

A Non-B visa/extension allows multiple Non-O dependent visas/extensions, but it doesn't mean that the employer must support them. It's all up to the employer and the contract between you whether they let you do so or not.