so i plan on useing this design that i dound on the internet (Diy Dwc for cannabis growing), its a simple dwc design but im woundering if anyone could tellme whats going to be the best way to add nutes and change rez, etc...

I'm in the same position. The simplest way to change the rez is to lift off the lid and put it onto another bucket. Then clean out the rez, fill it up and add nutrients, and put the lid back on. But thats a chore if you have a few plants.

another method I came upon is what this guy does
Lets Build a Bubble Bucket *Step by Step* - Grasscity.com Forums

He has a separate bucket full without a plant in it that is connect to the other buckets through a hole near the bottoms of the buckets, so he can just fill that one bucket and gravity will feed the water to the other buckets with plants in them. read through the thread and it is explained