Exfoliating? Serum? Toner?

Best to go with products that have salicylic acid. As you have sensitive skin, I would suggest going for a cleanser because you rinse it off, the concentration is low and it's less likely to irritate the skin. Most of them you can use daily. Toners and serums are normally slightly more irritating as they stay on your skin. You can either go for concentrations below 1% and use them more frequently or go for 2% and use a couple of times a week. I personally prefer serums, but that's just my own experience. Whichever type of product you prefer, make sure you ease into it.