1. Having Wi-Fi on your motherboard should be the least of your concerns since you can get a USB Wi-Fi adapter on amazon for $10.
2. GPU prices are probably not going down this year. However, don't give yet because you can get a shiny new 3000 series GPU from micro center, if you can go to micro center very early in the morning (like 1 or 2 hours before they open) you could possibly get a chance to get one. If you check the micro center website it will tell you what graphics card are in stock at your location. I got my RTX 3070 founders edition from micro center using this method btw.
3. You should definitely get AMD considering that the Ryzen 5 5600x and Ryzen 5 5800x can be found basically anywhere (including micro center) they are a killer deal for your price point
4. You should start by trying to secure a good graphics card, if you can do that then the rest of the parts will be easy to get. That would be the best way to know if you should build it or not.
5. If you are going for that flashy build, then I would recommend buying a good case with a medium amount of RGB and going for all RGB fans and putting some LED strips around it.