1,2,3) I don't really use a unit size as most of the markets I bet are pretty small and have low limits. I generally just max everything. On sports where I can bet more than where I'm comfortable maxing (NFL, team sports, etc), I bet 1/4 kelly. Interestingly this leads to a situation where my mean bet is about 20 times the size of my median bet size.
In terms of bankroll advice I would give for other people, it depends quite a bit on their situation. I would say, most people with the ability to beat sports (including myself here) underbet their bankroll. While most people who can't, wildly overbet it.
4) In terms of actual dollars, MMA is my most profitable sport, followed by NFL. In terms of ROI, it is by far Entertainment bets, including award shows, then Golf. My least profitable sport is MLB.
5) It really depends on the sport. In something like Entertainment props, things often just "look" off to me. Years of looking at lines and having a decent understanding of how things tend to play out makes it sort of automatic. A lot of times these props are simply thrown up by books while doing very little research. For example, this year Bovada set the line at Entourage doing over/under 30 million dollars opening week. 15 seconds searching online would've shown that was a bad line.
6) The books I always recommend are: Sharp Sports Betting, Weighing the Odds in Sports Betting, and Conquering Risk. These are basically beginners books. I would also recommend Thinking, Fast, and Slow by Kahneman. Judgment Under Uncertainty, by Kahneman and Tversky. Any good introductory statistics textbook. And maybe most importantly Fooled by Randomness, which completely changed the way I thought about betting markets.
I have begun writing my own book as well, which I am still unsure if I will ever publish. The damage it could do to my bottom line might not be worth the money made from selling it!