Best Build for 1440p Competitive Gaming and Development?

I'm looking to build a high-performance PC with a budget between $5,500 and $7,000, but I might stretch a bit more if the performance gains are significant. My top priorities for this build are competitive FPS gaming at 1440p with a refresh rate of 500hz, software development with heavy IDE usage, and some occasional 3D rendering in Blender.

So far, I've considered the AMD 9800X3D or 9950X3D CPUs for their gaming capabilities and multithreaded performance. For the GPU, I'm thinking about the RTX 5080 or 5090, depending on whether the price difference makes sense for my needs. I want at least 32GB of DDR5-6000 RAM, but I'm open to 64GB if it really benefits my workflow. Storage will be a dual NVMe setup just for booting and games.

I have a few specific questions:
1. Is the 5090 an overkill for my competitive FPS gaming and light Blender work, or does it justify the price?
2. Should I go for the 9800X3D or 9950X3D? Will I really feel the extra cores in software development tasks or is the 3D V-Cache benefit similar in both?
3. What recommendations do you have for the motherboard, case, PSU, and cooler that will ensure optimal performance?
4. Are there any potential issues I should watch out for at my budget?
5. Lastly, is it worth waiting for the Zen 6 or next-gen processors, or is now the right time to buy?

I want to make sure my case fits under 21.4" tall for my desk space, and I'm buying from Micro Center in Paterson, NJ, keeping an eye out for bundle deals. Any imminent launches that could change the situation in the next couple of months? Thanks for your help!