Convert UEFI Windows 10 laptop to a dual boot system using "something else" install path

Ubuntu 14 dvd installer couldn't sense the existence of Windows 10, so it was either "something else" or "wipe out Windows and take over the whole machine"

The story so far:
I have shrunk the biggest partition to free up some space using the ubuntu installer's partition thing:
Here's a picture of before and after

Note: UEFI somehow lives on /dev/sda1, right?

As you can see in the second link, Ubuntu installer now asks for "Device for boot loader installation". I don't know!
Is that /dev/sda - like nearly every pre-uefi guide says?
Is that /dev/sda1 - will it be smart enough to just 'hang out' with the Win10 files there?