BitLocker drive encryption questions

[tarmiricmi]

Hello,
I have two PCs that I wish to encrypt with BitLocker (system drive encryption). Windows 10 64bit 1607 on both PCs, identical 256 GB SSDs with similar free space.
On first PC, encryption went OK. It offered me to save a password (or whatever that is). There is no option for BitLocker separate password (other than PIN that I use with Windows 10).

On second PC, it is offering me an option to create new drive from free space (?).
https/i.imgur.com/DZajYY5.png

I want to encrypt whole system drive.

Now why does it ask me on 2nd PC, what it means - will I have less free space or what?
And why on 1nd PC there is no separate BitLocker password? Is the drive encrypted so that one can't access its file system when for instance plugging it to another PC? When using Veracrypt, one must define password which is used prior to OS booting.
Can I use Windows upgrade (for instance to 1709) when BitLocker encrypts the system drive? With Veracrypt this is a no-go.

Thanks in advance.

 

[ex_bubblehead]

The second PC's drive does not have the required hidden 'system' partition, which is needed for BitLocker, and will be created during the encryption process. The first one did have that partition present.

For all upgrades you must first 'pause' BitLocker. Then, once the upgrade is complete, 'unpause'. Same goes for such things as updating BIOS. If you don't go through this process you will be needing the recovery key to get into your system. Better make multiple copies of it and keep them secure. If you lose that recovery key you will lose access to the contents of the drive......permanently.