Before my husband and I got married he owed Federal taxes that we have been making payments on. *If we both filed separately, would the IRS take my refund to cover his owed amount?? * We also have a child... *Can I claim the child as a dependent as long as my husband does not?*

From my understanding you can actually still file jointly and you can merely file a "injured spouse" which allows you to get back your percent of the refund.
At least this was what we used to do, I am sure another tax expert will let us know if and how it is still done.

Fr Chuck is correct. You can file Form 8379 as an Injured Spouse and get your share of the refund.