How is that possible? My manager doesn't even work at my office, so how exactly can she give me an annual review, and is this a good sign? I've never had an annual review,with any of my employers before

Never had a review? How do you work on job advancement? How do they know how or what you do.

Perhaps 'annual' really means 'year end' in your company.
70 days is an odd time to have a review.
It's a review of your file - things like arriving on time, how many days out sick, complaints, and work performance as determined by your immediate superior.