Regarding W-4 Question
Generally speaking, as a taxpayer who is filing married filing joint tax return, you are entitled to claim 2 allowances on the W-4 Form assuming you have no children or dependents (you would be entitled to claim 1 additional allowance for each dependent).
Thus, your husband should claim 2 allowances, and this would generally result in little or no additional tax liability at end of the tax year.
Similarily, when you get a job, you should also claim 2 allowances on your W-4 thus, you would have paid sufficient taxes on your income from employement that is reported on Form W-2.
However, if you have any other income such as capital gains, rental income, substantial interest income or dividend income, then you would owe taxes on this amount and this could result in additional tax liability at the end of the tax year.