PocketBook 631 Plus, do I need to adjust the color temperature at all?

Question

Electronic books

I choose an e-book (I never had an e-book), I found the difference between PocketBook 631 Plus and PocketBook 631 Touch HD only in adjusting the color temperature. Who has a PocketBook 631 Plus, tell me if this feature is useful, usable?
Immediately a couple of questions on the topic:
There is a cheaper model PocketBook 626 Plus
1) It has 2 times less RAM (256 versus 512). Does the RAM really affect the reader at all?
2) Also the difference in display resolution (1024x758 vs 1448x1072) and pixel density (212.3 PPI vs 300.3 PPI). Is it noticeable at all?
3) Well, the more expensive model has sound, the robot reads a book, well, there are audio books. It was really useful for someone, it’s just that in my opinion you can listen to audiobooks on your smartphone, put it in your pocket and go and listen to yourself. Who has an opinion about the need for this parameter?