2) This is really my weakness since my stats and linear algebra are passable but not great. There are several free datasets (mostly from data.gov) that I've been playing around with. Should I "publish" the results of my practice studies on a portfolio-esque site? Or is it sufficient to just know the techniques well enough to answer interview questions?
3) I'm fairly well acquainted with machine learning - my interest in machine learning is one of the driving forces for me to take up neuroscience as a career.
4) Great information, thanks. I'm glad to see people use technology more as a scratchpad and less as a regimented "You must know XYZ tech stack". R and SciPy are on my to-do list, I'll add Map Reduce.
As a machine learning guy in an analytics department, are you hunting through internally generated numbers to find trends (like sales, ad placement, etc?) Or are you hunting through externally generated data to find new trends/products/markets?