As for medicine preventing evolution, that is simply a mistaken belief based on the general poor understanding of evolution common in society. Evolution is measured as the rate of genetic change in a population. Selection *slows* this process - it is a break on evolution - as it limits the rate of genetic change by selecting for or against certain genotypes. In the western world we've greatly reduced the impact of selection - ergo, we as a species are accumulating mutations faster, and thus are evolving faster than before.
Not my area but I know the above is an older hypothesis more recent evolutionary studies use a slightly different hypothesishttp://en.wikipedia.org/wiki/Effective_evolutionary_time
No, the above is exactly what those of us doing work predicated on evolution (i.e. me) use as a definition. Your link refers to a concept that isn't even relevant to the discussion at hand.
But, since you brought it up, the effective evolutionary time hypothesis is fundamentally flawed - it only holds true for a very small subset of species. Most domains of life do not show latitude-based biases in species number distributions. Its only a few exceptions (large plants, some exothermic animals) that do.
Both are unproven but the newer hypothesis has had some success where the older hypothesis fails.
No, the statements I made are proven, and are concepts derived in the new synthesis (circa 1936) that has stood the test of time. Selection limits the rate of acquiring new genetic material, and the maximum rate you acquire new genetic material is determined by your mutation rate.