imac pro operation premiere computer hardware selection

[#1]

I am a video worker. I expect to switch to an imac pro within the next three years. I will mainly use Adobe software: Premiere edits videos, most of which are Full HD files. In response to the popularity of 4K videos, the frequency of using Media Encoder for transcoding will increase. Come higher. AE and PS will also be used, but mainly editing files and transcoding. It will also work with arrays.
If you want to edit smoothly and have a limited budget, what part should I upgrade first? Memory, graphics software, processor?

Thank you!

The equipment expected to be used is as follows
：
https://www.apple.com/tw/shop/buy-mac/imac-pro/3.0ghz-1tb#

[#2]

I am a video worker. I expect to switch to an imac pro within the next three years. I will mainly use Adobe software: Premiere edits videos, most of which are Full HD files. In response to the popularity of 4K videos, the frequency of using Media Encoder for transcoding will increase. Come higher. AE and PS will also be used, but mainly editing files and transcoding. It will also work with arrays.
If you want to edit smoothly and have a limited budget, what part should I upgrade first? Memory, graphics software, processor?

Thank you!

The equipment expected to be used is as follows
：
https://www.apple.com/tw/shop/buy-mac/imac-pro/3.0ghz-1tb#

[#3]

PLEASE!