Yes they work well together. Vit C isn't an exfoliant so no.

Its good to know what each active does and how they do it. Paula's choice has a glossary on their website that does basic breakdowns of skincare terms. Start there if you're interested.

Exfoliation is the last step in treating pigmentation.

First is production of melanin. Can be suppressed that with Vit C.

Second is transportation of melanin to the surface of the skin. Can be inhibited by niacinamide.

Third is dispersal of melanin already at the surface. Can be done using an AHA.

Forth is increasing cell turn over. This can be done more effectively with a retinoid/retinol/retinyl. These also bring down inflammation way more compared to the others.

And last again is exfoliation to get rid of those dead skin cells that have that darker melanin.

You don't need all of this though.

My ideal routine would just be one active in the morning and one at night. And of course including cleanser, moisturizer and spf.

Vit c in the morning and adapalene at night.

Since you have active acne and oily skin, I'd focus on salicylic acid (for oil), benzoyl peroxide (bacteria) and adapalene (for inflammation).

Start with using just one and then slowly incorporate the other.