I was searching for days to answer all of my questions related to this topic, but I had no success, until I asked it on PROHARDVER!.

At first: I was afraid what will happen with the wearing level on my Samsung 830 SSD, will the partition alignment and TRIM be OK…
Then: I did not know anything about current hardware support of Ubuntu.

A short how to how I installed Ubuntu on my system:

1. Since I was using Windows 10 I have disabled “Fast Startup”, checked BitLocker is off and turned off hibernation (powercfg /h off).
   

2. Disabled Fastboot in UEFI
   

3. Also disabled Secure Boot (Switched to “Other OS”)
   

4. Booted from UEFI pendrive.

5. Created an 1024MB fat32 primary partition (with the label “EFI”) with a free space of 1MiB preceding

6. I have 16GB of RAM so I created a 16384MB swap partition with linux-swap file system.

7. The rest (without the 10-15% provisioning space) went for / (root) with ext4.

8. Agreed the UEFI install warning
   

9. Then the install method was the same like on a BIOS machine.

10. I have installed fglrx for my Radeon R9 270X

11. Turned volume to maximum in alsamixer for my Xonar DS in Master Front
    

12. That’s all!

Thanks for reading!

Sources:

Secure Boot settings (Image), Fastboot Settings (Image), UEFI settings (Image), Message (Image)