I would toast the oats. Im a fan of home toasting base malts in ipa's myself also. Its not really a whole lot of oats,Ive used more in my small batches. Its your call to wait on the crystal malts, for a black Ipa personally I like to add the crystal malts,yet you should still get a good beer otherwise and you will get more of the munich character solely which may be good enough. With or without they are still going to be different beers depending on how much crystal malts you were going to use. In that recipe though I would add more oats to get more character in that black ipa if not using the crystal malts- thats just my preference also though . Youll get some nice creamy head retention too. Ive never found Ive over oated a dark ale before.Although the more you use it could make some haze to it probably. Ive still had them clear up pretty brilliantly though without additives.