TRSS is spot on, on both accounts. It's up to you if you want to partition or not. I've used a 1TB HDD before w/out partitions and never had a problem. The only downfall with using such a large drive is the search indexing the OS has to do to locate a file, that is if the HDD has a lot of data on it.
This is my suggested setup.....1st boot drive - use an SSD (250GB - they are lightning fast) for OS and Office suite and what other primary software you want.
2nd drive - 1TB or 2TB, partitioned into 500GB blocks to use as storage labeling each partition w/a name. It makes storing/finding
data so much easier.