I think we've already been through this before. This question is what prompted me to post the pictures of the 24x and 40x burns in the first place. The same answer applies: not necessarily, and you need to try it yourself with your burner/media/reader to get the definitive answer. In any event, don't expect that error levels will go linearly with recording speed.
As for not having a 1x burning speed, it is likely because the drives have been optimized for higher burning speeds. Also, there isn't much demand for 1x burning, understandably, so manufacturers don't want to bother spending money to support it.