I notice that only the sensitive one is unscented and has glycerin in it. Does this mean that it’s more moisturizing than the others?
Most of the other bars have extracts and oil in them like this shea butter one has Butyrospermum Parkii oil. Does the oil have any benefits on skin?
Do the extracts and oils do anything or are they just there for the different scents? Are the dyes in the bars bad for your skin?
What about the anti-stress one with blue chamomile and oats in it? Would the oats be good at soothing the skin?
Yes, the sensitive one will be the most gentle (I wouldn't call it moisturising - no cleanser really is, less stripping is the most we can hope for). The extracts in other bars are added in very small quantities, so their real purpose is to support the marketing story. The dyes in the bars are not particularly worrisome (they stay on the skin for a very short time), but they don't have any benefit either, so it is not a bad idea to avoid them just in case if your skin is sensitive.
I would not recommend the "anti-stress" bar for sensitive or "stressed" skin - it contains parfum and not enough oats extract to have a benefit.