Questions before buying Windows 10 OEM

Hi!

I am new to this forum, so at first I would like to say "Hello" to everyone.
Then I would like to ask some questions if possible:

1. In case I buy a copy of Windows 10 OEM from a local reseller, who sells a "Hungarian" version of the OS in my country (maybe just only the hungarian lang pack is integrated) can I activate OS's with other language?
2. Windows 10 ISO

If I download the iso from this official site and use WUDT to create a bootable pendrive, can I activate it withy my OEM key?

3. In case I change my CPU (or replaced by RMA) will my Windows still be activated?
4. In case I change my motherboard what will happen? I have to buy a new licence?

Thanks for your help. :)

Thank you for your answer, Brink!

Q1/2) So in that case if I don't have a DVD drive in my setup I cannot install the product, right? In this situation I can borrow a DVD drive to install or to create an iso from it to use with WUDT. So to clarify that: Which can be found on my previous link is only for retail customers not for OEMs. What if my installation media got corrupted/broken/etc? I have to ask for a replacement directly from Microsoft? I know I can buy the software itself on USB drive, but unfortunately it is not available everywhere, that's why I asked about the regular way.

Q3) So I can go for an FX without any fear later this year. That's cool.
Q4) They only reactivate an oem license in case of RMA if I am not mistaken. Or if I call the support and tell them the actual situation they'd activate it or because its against - well... i paid for it, so I am not a "sticky fingered" pirate or something like that - the licensing rules or terms, they will say something like I don't really want to hear after spending 160$?