The only thing I found really effective for spidermites is abamectine. If you can find a product with it you can spray it on the fan leaves but not the buds/sugar leaves. That's often hard to do but with your two rather smallish plants it should be pretty doable.
It's non systemic but stays in the cuticle layer and kills every mite that tries to feed on the fan leaves. That often works well cause those little bastards don't like the buds when they start to get resinous and sticky, so they have to retreat to the toxic fan leaves if they aren't enough yet to put webs over the buds.
I always recommend, and do so myself, to spray abamectine twice, first time after a Clone is established and a second time about a week after the flip before they start budding. That way spidermites will never be a problem again and your buds stay clean of nasty stuff like neem, oils or worse. I do it every run, not when I have mites but as precaution. Only thing that's important is to use the right concentration so they get killed for good and don't develop resistance!
Neem hasn't been more effective than hosing down the plant with water for me and all other things I've tried where more a desperate band aid than a fix in my experience. Others experiences differ, spidermites can be harder or easier to kill or control depending on a lot of things.
So I can't give advice on anything else. Except spraying plants with water and as much pressure the plants can take. That's not a solution but it'll buy you time till you've got something on hand.
About the AN, you can try it but I just wouldn't recommend it for beginners. Simple formulas like Lucas, two or one part nutrients are really nice cause you can concentrate more on other aspects without worrying what to put in you nutrient solution.
As you can see with the mites there is a lot to keep an eye on so it's a plus to have a simple solution for feeding. Especially if your starting your first grows with Dwc.
When you've made your first couple grows without major problems I'd say it's time to slowly start experimenting.
Always one step at a time, patience is the most important skill I had to learn for successful gardening!