The memory QVL is at https://dlcdnets.asus.com/pub/ASUS/mb/LGA2011/Rampage_V_Extreme/R5E_QVL.pdf?model=RAMPAGE%20V%20EXTREME
My understanding is that Haswell-E/X99 gets pickier after 2666MHz, so I put a Corsair 16GBx4 CMK64GXM4A2666C16 kit in my GA-X99-UD4.
It seems like your board could a 8GBx8 kit of CMK64GX4M8A2800C16 for 64GB at 2800MHz.
I'd start by Googling e.g. "14700K recommended coolers".
https://tech4gamers.com/best-cpu-cooler-for-i7-14700k/ looks plausible.
https://skinflint.co.uk/?cat=cpucooler&xf=16454_253~817_all1700 shows all coolers for Socket 1700 that are explicitly specified to meet or exceed its 253W TDP. You might also consider a slightly more relaxed 250W search: https://skinflint.co.uk/?cat=cpucooler&xf=16454_250~817_all1700
If you prefer a watercooling kit: https://skinflint.co.uk/?cat=coolwsets&xf=4666_all1700
I've never used watercooling (I fundamentally dislike the idea of water sloshing around inside my computer, plus the failure modes seem a bit less predictable and more sudden and total), but the tech4gamers article suggests that a >360mm radiator might be appropriate for these CPUs.
According to https://www.intel.com/content/www/us/en/products/sku/236783/intel-core-i7-processor-14700k-33m-cache-up-to-5-60-ghz/specifications.html the 14700K base power is 125W TDP, but it can turbo boost up to 253W TDP (the 13700K is the same, by the way).
Do you mean the Coolermaster ML240L v2? https://www.coolermaster.com/uk/en-gb/catalog/coolers/cpu-liquid-coolers/masterliquid-ml240l-v2-rgb/#specifications says it can handle TDPs of up to 180W by my reading. Enough that the 14700K won't be damaged, but... it'll probably hit thermal throttling under peak load, resulting in poorer performance than with a cooler that can handle 253W or more.
The 14700K and KF are a very recent refresh of the 13700K.
They should be priced similarly, and they should perform a little better in productivity applications, and have some extra features (e.g. https://www.intel.com/content/www/us/en/support/articles/000095419/processors.html). Unless you can find a very good price for the 13700K, pick a 14700K or KF.
The 14700K includes a built-in GPU which the KF does not. Some streaming applications may use it to encode your stream, and it may help in some other applications (e.g. Corel Painter) if you use those. It may also come in handy if you have a discrete GPU, but it fails, and you need something whilst it's being repaired or replaced.
5820K+4070 here. Happily playing games at 4K@60FPS, or better (sometimes requiring DLSS, admittedly). I was hoping Sapphire Rapids/W790 would be as economic as the X99/X299 HEDT platforms of old, but that's not really the case, even allowing for nearly a decade of inflation.
I can see me reluctantly settling for the mere 2-3x performance gains of a 13700K/14700K unless something better - and yet still economic to buy - arrives.