Just placed an order on gemfive. Can't wait to get the phone soon

I just got my phone delivered to me this afternoon. Bought it from gemfive last Sunday and the box is sealed.

After using for several hours today, I am overall very satisfied with the phone. Sensitivity is one thing that need to get used to as I noticed the phone will not register the touch if it is still scrolling (even a tiny little bit)

Being my first Huawei phone, there are stuff that need to get used to as well.

Want to ask the sifus here, usually will you all charge the phone using the original charger (meaning using quick charge) or use the traditional smartphone charger (5V/1-2A)? I got a Xiaomi powerbank or two lying around and it is kind of a waste if using original charger is better for the sake of battery lifespan.

Sorry if asking noob question. What is "ROG power saving mode" ? Where can I see this option?