Good screen 15-17 laptop on a tight budget

[Asanoth]

Hello,
so, my old Asus K52JC is starting to literarilly fall apart, albeit it has been serving me well for years.
i3 M350 2,27 GHz 64bit, 4 GB RAM, GeForce 310M 1GB + Integrated (nVidia Optimus), SSD Crucial 256 GB + HDD WD Blue Mobile 2TB in a DVD caddy (both upgrade)
This power is enough for my use, except for I started to shoot photos into RAW and when developing, my CPU goes to 100% and stays put: and most changes takes soooo long (in noise reduction, or sharpening, we are talking tens of seconds - luckily I bough a noise-free fullframe camera ). Also, sometimes I do some recording into a VST/VSTi and there the CPU is not holding up as well. All of it is amateur work as a hobby, so I do not need a pro setup.

Originally, with a budget of 800€ I was deciding between something like Probook/low-end Latitude and something like Vivobook/Swift/Aspire: I wanted a good quality build, some i5-i7 power, and couple of other things, blah blah blah - and then I found out the story of laptop screens and their 60% sRGB gamut :-/. Ok, it s not a big deal with my Asus (however it definitely has a TN, so maybe it has good colours, who knows...), but if I am buying something new, I want it to be somewhat "not that bad".

So, my priorities swiftly shifted and now I am basically looking for a laptop with a good 15-17 screen and two harddrive slots. Its performance should not be too weak, but it is not a priority. The issue is, I do not think there are any laptops with a decent screen under those 800€, maybe not even under 1000€, and I am not even considering the build quality if they were. Eventually, these options crystallized as I did some research:

a) Fetch in some 100s €, wait after Christmas for sales and buy a new laptop with a decent screen (Yoga 730, Zenbook...). The question is, how much will I need to add, which laptop should I buy and if it's worth a poorer build.
b) Buy a used Dell Precision 5510/7710, p50, Zbook etc., or some business equivalent, which do not come with great screens anyway. Workstations are a bit overkill, I do not need that much power and especially a GPU, but they come used to the market more often, than good screens Elitebooks/Latitudes/Thinkpads. In this case, I could get something with i5/i7 6XXX and HW of a similar age, but there would be no warranty. However, people say these machines are built to last...
c) Buy a refurbished workstation, but there I could only get to Zbook G2 or Precision M4800. 4th generation intel core and 5 or so years old: I feel that it too much for an electronic device, which have been heavily used, but maybe I am wrong.
d) This came to me as a sci-fi idea, buy a Probook/Vostro/whatever, new or barely used (i do not think there is such a thing as "barely used probook" for sale) and buy a good (used?) laptop screen and swap it for the original. I do not, however, see how that would come in expenses and I believe that eventually it would get more expensive than any of the options above. Plus warranty issues plus it seems like a nuissance to do...

So the question is... What should I do and what should I buy?
Thank you .

PS: Apart from that, I also have some technical CPU questions:
a) Do I need a 4 core (my RAW SW can use multiple cores)?
b) Is i5 enough or should I focus on i7s?
c) Should I consider Ryzen? Given the price I gladly would!

[Asanoth]

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