Generally it's easiest for dual booting to install Windows first - this is because once you install Windows it'll over write the GRUB bootloader and not give you the option to boot into Linux.
It's just a recommendation though - you can easily repair GRUB using Rescatux boot disk, or just boot of Ubuntu Live USB and install\run boot-repair package.
Now for the half NTFS, in Ubuntu firstly install gparted:
sudo apt-get install gparted
Open up GParted, resize your partition by shrinking the available space to how big you want the NTFS partition to be.
You will be left with your Ext4 Ubuntu partition, and then a grey 'unallocated space'
Click on that unallocated space and make a new partition with it, select all the space free and select the option to format as NTFS.
When you go to install Windows, you can click the NTFS partition and choose to install there.
How to Partition Your Hard Drive for Ubuntu and Windows
Edit: As mentioned once you successfully install Windows you will lose access to Ubuntu on the other patition when booting, and as mentioned do a search for Rescatux or Boot-Repair for Ubuntu to restore GRUB