Here are three computer suggestions on https://shop.presonus.com/products//PSc-Rok-Rak-PreSonus-Certified-Computers
These can give you a great idea of pre-configured systems that work great with Studio One.
I personally prefer desktop systems because you can control things better on the component level. Laptops are not as self serviceable in my opinion.
In regards to your HD question. Yes, it is better to use multiple HD's. Have one drive that is a minimum 7200 RPM drive as the main system drive. The OS and applications will be installed and run from this drive. The second drive also should be a minimum 7200 RPM drive, will be for your SoundSets, sample libraries, storing Songs and Projects.Never use 5400 RPM drives.
Hope this information helped.