if you got some layers going with a pure wax or a sealant, better not use a cleaner wax muna. not unless you want to remove the previous ones (and albeit some minor swirls that will always pop up) and start from scratch..

you have to find a balance between looks and protection especially sa weather natin ngayon.

pero clarification lang, when you mean by layering, what products are you using?
personally, maganda kasi ang results to get 2-3 layers of Klasse SG first before topping off with carnauba on dark-colored rides.

as for #20, I spotted some sa Simex sa may Kamias. yun nga lang, medyo mahal. I'd rather pick #21 or even better, Klasse na lang.