If I visit a site 100 times a day (from one IP) does Google Analytics track that as 100 unique visitors?
According to this article, visitor uniqueness is determined by using cookies rather than other identifying factors (such as IP address, browser identification string, etc.): https://www.google.com/support/analytics/bin/answer.py?hl=en&answer=33087. This means that you will be counted as a single visitor as long as you do not delete your GA cookies -- and even if you change IP addresses while browsing.
No. Google uses a cookie to track visitors so that counts as one. This video explains in detail: