You probably don't need the Carapils, the wheat will provide head retention.
I've never used acidulated malt, so I can't be much help there. A quick Google gave me
this, which says acidulated is good for lowering your mash pH, and will provide a sourness.
I think the sourness is more typical of a Berliner Weisse than a Bavarian Hefeweizen...is that the flavor you're after? If so, and if you're afraid of the acidulated, I'd say leave it out. You could always add lactic acid to the finished product to get a similar result.