How to reinstall Windows 10 on new hard disk
Since I have the free version of Windows 10 pro, can I still reinstall it a new?
Just download the Windows 10 .ISO and when prompted for a product key, skip it that step, once installed Windows 10 will automatically activate because of the original digital entitlement you received when you performed the upgrade. Windows 10 for this purpose, considers the same motherboard, the same machine.
Does the windows 10 installation offer disk management and partition like the older Windows installations used to?
It uses the exact same tool. If it didn't contain the tool it wouldn't be able to create partitions automatically.
How should I reinstall Windows 10 x64 the easiest but still remain on free mode?
There isn't a "free" mode. Once you perform the upgrade once, you have a permanent license to Windows 10, which can be installed on the same number of devices, as the previous version you upgraded from. I have previously answered the question about how the upgrade works here.
There is absolutely no difference between the version of Windows 10 you receive if you purchase Windows 10 from a retailer or accept the upgrade when prompted while running an eligible installation of Windows. The only difference is that you won't receive a unique Windows 10 license key. User who upgrade to Windows 10, through an eligible installation of Windows, are activated through a digital entitlement system. Users who purchase a retail license from Microsoft actually receive a Windows 10 license.
Starting with the Threshold 2 update, Windows 10 will both accept an eligible Windows license key at installation and activate with an eligible Windows license key. Windows 10 RTM (Release to Manufacturing) does not have this capability.
If you want to continue to use the Insider Preview free builds, you can start by installing using the tool that Microsoft released. Skip the product key when asked.
Disk management during installation should be similar, but I have not done a clean install yet so cannot confirm.
I have tried this myself. New installation will not activate again. You can also refer to this official post:
https://answers.microsoft.com/en-us/insider/forum/insider_wintp-insider_install/pre-release-product-keys-for-windows-10-insider/97e6cd1f-ee8a-42ea-b76c-46aa4af8e203?tm=1437003762162
Quote "We hope Insiders will continue to test Build 10240, which is only intended to be installed as an upgrade from a previously-activated version of Windows 10 Insider Preview – we do not support clean installs of Windows 10240"
(10240 is the RTM release)
On the other hand, I had success in using the included System Image Recovery. Which is basically a partition backup. To use it, you should have an additional storage formatted with NTFS (or a lot of DVD-R). You should also shrink your system partition such that it will fit in your SSD. I would also recommend performing Disk Cleanup and removing old System Restore backups.