Clean re-install of Win10 question re activation

I'm upgrading a friend's laptops (yes a Celeron!!! & a 2nd Gen i5, lucky me) from HDD to SSD, increasing memory and reinstalling Win10 using a W10 USB drive that I'd done a year ago using MS MCT. So my first question is

During the installation process I presume I skip the step which asks for a product key and select the option 'I am Reinstalling Windows 10 on this PC'. Am I correct in assuming now all activation takes place via a digital entitlement stored on the Microsoft Servers? Since I'm upgrading memory & storage isn't this going to change the devices digital signature quite a bit. So how will MS recognise this as essentially the same laptop or has this digital recognition thing moved on. As I seem to remember cases where people had to ring up MS after upgrading various components (I assume motherboard upgrades would still throw a spanner in the works)

My second question is if I now wanted to create an up to date Win10 USB drive using MCT can I just as easily do it on a third PC if say it ran Win7 (fully activated of course)?

Appreciate any help

Yes to both those questions. It will activate via ms servers and the hardware shouldn't effect that I have done similar with no problems. You can create a USB on any PC be sure to get latest ISO or you will have massive updates and let ms create it at the end

Thank you folks very helpful :)

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Incidentally I gave a thanks to idgat and then tried to do the same with Samuria and it said ...

You must spread some Reputation around before giving it to Samuria again

Huh?!