There is minimal difference across brands for RAM power consumptions as they follow JEDEC standards. Increasing RAM capacity very slightly increases power consumption but it’s not noticeable. The best option is just to get the cheapest 5600 mhz kit (unless you want to game as well in that case you might want to look for a CL40 kit).
For the speakers, you should use the stock ones as they get a lot louder and sound better when paired with the AMD board. As for the wifi card, either will work. Personally, I decided to use the Mediatek one as per Support’s recommendation and I’ve found that the range and speeds are a lot better than the AX210. But you’ll find people who say different things about both.