AgentZero writes: "As for the whole whether or not an FTL race would have found us by now, I think most arguments are flawed by assuming that an alien race would have even remotely the same motivations as our own."
Obviously it's tough to generalize from one data point. It seems reasonable to suggest, however, that both biological and cultural evolution favor expansionism in intelligent species. Biologically, species that don't try to increase their numbers and ranges tend to get wiped out by competing organisms and/or environmental changes (ice ages, asteroid strikes, etc.). Culturally, stagnant civilizations are usually overrun by vigorous expansionist competitors. If a sapient alien species is as culturally diverse as our own (e.g. because of varied planetary habitats), even a SINGLE expansionist culture would end up determining the character of the whole race.
The same principle holds on a larger scale. Perhaps evolution for some reason favors introspective sentient species. Maybe the universe is full of "flower children" who make love (with birth control), not road trips. If so, then FTL doesn't exist, because it takes only ONE vagabond culture in ONE species with practical FTL and a billion year head start to put ALL the hippies out of business.
With STL only, the same thing should happen on a galactic scale, so I can buy the argument that we're either first or alone (more or less) in the Milky Way, as unlikely as that appears. There are of course other possibilities, some of which we've already covered.
AgentZero also writes: "Our solar system is located in one of the arms of the Milky Way's spiral, now does that make it part of the older (first to form) or newer parts of the galaxy?"
According to the article below the first stars in our galaxy formed about 13.6 billion years ago. That makes our sun, at 5 billion years, a relative youngster.
http://www.space.com/scienceastronom...ge_040817.html
I assume that 13 billion years ago local conditions could have led to star formation just about anywhere in the galaxy, but most "old" stars formed near the galactic center and in the galactic "halo" of globular clusters. Spiral arms are areas of new star formation that shine brighter than the rest of the galactic disk due to the very young blue giant stars within them. Our solar system has been around the galaxy 18-20 times since it was born, so our current location in a star forming region is a coincidence.