32GB SSD is enough for Ubuntu if you don't install lot of large applications in Ubuntu that consume a lot of disk space.
Ubuntu will be able to access the 1TB HDD having Windows 10(Windows 10 will not be able to access the 32GB SSD which will have Ubuntu). I recommend you to shrink the Windows 10 partition on the 1TB HDD and create another partition(of NTFS file system) so that you can use it for data/stuff which can be accessed by both Windows 10 and Ubuntu. Due to this setup, if you later on encounter problems in either Windows 10 or Ubuntu, your data will be safe and you can access it from the operating system which is working properly. Even removing any operating system will not remove your data as it is in a different partition.
Since Windows 10 doesn't shut down completely(by default), therefore you won't be able to mount Windows 10 in Ubuntu 16.04. In order to do so, you have to disable Fast Boot in Windows 10. You can do this by going to Control Panel -> Hardware and Sound -> Power Options -> Choose what the power buttons do -> Change settings that are currently unavailable. Then scroll to the bottom of the window and uncheck Turn on fast startup (recommended) box. After that, shut down Windows 10 and then boot into Ubuntu 16.04. You will find that Windows 10 partition(which is NTFS type) gets mounted easily !