Yes, if this is where you are installing windows to again.Will fresh installing Windows 10 delete all the content om my C/ drive?
Yes, if this is where you are installing windows to again.
A clean install is absolutely best practice so you don't carry over residual junk and potential conflict files over to new hardware.
You can clone, just clean install is better.
If it's a new motherboard, whilst it's not necessary, it may be worth seeing if it has the additional 4 / 8 pin CPU power and if your PSU supplies it.
Just saying as I don't know what MB you have purchased. Many newer boards come with an additional 4/8pin CPU power connector. Which many older or weaker PSU's do not have.I am sorry, but why should I check for an additional 4/8 pin connector?