Just keep in mind that the Onedrive 200GB deal is only for one year, and after that you have to pay a subscription. Having a portable HDD if you have particularly large and many files may be more efficient and/or cheaper, depending on your needs.
Just wanted to correct one thing about that statement - the 200GB OneDrive deal is good for 2 years, not just 1. Also - the subscription costs for OneDrive are amongst the lowest out there, with that same 200GB only costing $100/year (under $10/month - relatively inexpensive).
I would recommend the Pro 2 for your needs, and at least 128GB. If you can manage OneDrive cloud storage and 128GB local storage appropriately you should be able to manage just fine. If you feel you need a bit more local storage opt for the 256GB/8GB ram combo. It's pricey, often out of stock, but I think does provide a lot of bang for the buck in a small form factor. Make no mistake - there are certainly other laptops you can buy that will have similar if not better specs for the same money, but they won't be a Surface, nor have some of the best pen/WACOM support you can get in a tablet.
I just upgraded from a Surface Pro 64GB to Surface Pro 2 128GB, will be selling my Pro 64GB soon. I have to tell you, it's a rock solid machine. Absolutely not the fastest out there, nor the best for gaming, but it does happen to just about everything well which is why I think it's a solid machine.
I personally do Adobe Lightroom (RAM and CPU intensive), Steam Games (Borderlands 2 - OK), iTunes runs OK, just about everything I do runs great.