Upgrading to Threadripper motherboard;Backup & Thermal Paste Questions

Hey guys,

I currently have a pre-ordered the Ryzen Threadripper 1950X CPU:

https://www.newegg.com/Product/Product.aspx?Item=N82E16819113447&cm_re=threadripper-_-19-113-447-_-Product

And the Gigabyte Aorus X399 Gaming 7 motherboard:

https://www.newegg.com/Product/Product.aspx?Item=N82E16813145030&cm_re=aorus_x399-_-13-145-030-_-Product

My current PC setup is here, with the boot drive being the m.2 Samsung 950 PRO drive
https://pcpartpicker.com/b/BqHhP6

With Threadripper and the motherboard itself being new products, I am well aware of the possible bugs, issues, hiccups, and pitfalls that may come with it. The upside to this is, I am in a position where I can keep my current board and my Intel I7 6800k as backup in case something does happen to not work on the Threadripper setup.

I know that with Threadripper and the new board, I will need to re-install Windows 10 and install all the drivers for the new setup. My question is, can I make a complete backup of my current OS drive in case the Threadripper setup gives me some sort of issue? That way I can just swap the boards and CPUs back and be right back where I currently? All my other hardware is on the support list/compatible with the Threadripper setup. But again, with it being a new board/cpu, there is a chance there could be bugs that need worked out, and I may not wanna wait until they are all resolved. I already have multiple backups of all my other important data, but I was wondering if it was possible to make a back up of my current OS drive just in case the Threadripper setup flops.

Also, I just bought the Corsair H115i AIO liquid cooler a couple weeks ago, and it is on AMD's website as part of the threadripper supported coolers. I am aware that with Threadripper being a larger CPU/socket, overclocking with my current cooler may not be wise, and a TR4 socket specific cooler down the road maybe needed for overclocking (I don't plan on overclocking anytime soon anyways).

However, my concern is the thermal paste application. I have installed dozes of aftermarket fan coolers on dozens of CPUs, but this is my first liquid cooler. The thermal paste was pre applied to this cooler when I bought it. I have artic 5 silver paste, and I know that I have to clean off any current excess paste from the cooler before applying the Artic 5 to the new Threadripper cpu, but is there a different approach for threadripper with it being a larger chip? Or does it not matter because the cooler size is still the same?

I know there is a on-going debate of how to apply paste, but I do the 'smaller then a pea size in the middle' method and let the heat spread it to the chip. I know not EVERYONE does it that way, and I am not looking for a debate on the topic, as this method has always worked for me on all my builds. I am just not sure if I should be looking to apply a bigger amount with Threadripper being a bigger chip. I am assuming that the only time I will need to apply more paste is if I get a cooler that was specifically designed for the TR4 socket down the road?

Any feedback would be great! Thanks everyone!