Can the dehydrater is replaced by the 90% alcohol?

I know this is a old question but I’m going to answer anyway in case someone else has the same question. A great substitute for dehydrator, would be 100% pure acetone. To me, it’s a cheaper option that works exactly the same. It dries fast and it also helps the acrylic/gel last longer making it less likely to pop off. That’s the only thing I’ve ever used and works great. So really, the only thing you need to buy when it comes to nail prep is the primer. You don’t need the whole kit.

Is this smell very bad?

If you are sensitive to smells the primer stinks something awful. I can barely stand it. The chemical scent makes me feel like I'm breathing poison but I am sensitive to smells due to allergies. The scent doesn't last long. Once you close the bottle and it dries on the nails you don't notice it anymore.