Apart from the possibility of installation problems for a 1 TB partition, your ability to effectively image your HDD stands out.
I would go for a partition with OS and installed programs on a 100GB partition but not greater than 200GB (you have 1TB to play with). In my opinion this is the most vulnerable part of your computer system likely to fall over due to malware, OS/installed application bugs etc. You need to be able to image it on a regular basis (taking say ~ 30 min).
The rest is about how you manage and backup your data. I personally would go for another 2 to 3 partitions. You can do surface scans (for bad blocks) and partition data recovery on a more manageable partition size.
Edit: The inbuilt disk management tool should be sufficient for most of your basic partitioning needs. I regularly use the more flexible Partition Wizard but suggest you only the use the bootable version. The mini tool has let me down.