I really enjoyed this article for taking a smart and evidence-based look at risk. My background is in statistics and data analysis, and I've gone through a very similar process.
1. The mathmatical underpinnings of risk isn't that complex, but it's really difficult to put it in perspective. People are notoriously bad about assessing risk. There are like a zillion articles on this if you google it.
2. People get, understabably, very risk-averse about pregnancy (both the pregnant woman herself, and all the people giving her advice). People err way on the side of caution -- with a few notable exceptions, like certain kinds of invasive genetic testing that carry a very high risk of miscarriage. A lot of the risk of pregnancy is out of our control, so we sieze on things that we can control, even if they only budge the risk meter 1/10,000.
2. The best way to find out about causality is a randomized controlled trial. However, it's really hard to do a randomized controlled trial on a pregnant lady, especially about something involving risk. Say you wanted to design a study to find out about the effects of alcohol on the fetus. You would get a sufficiently large group of pregnant women, and you would tell some to abstain from all alcohol, some to drink one glass per week, some to drink one glass per night, and some to drink five glasses per night. Then you would measure the outcomes. Obviosuly, that study would be wildly unethical and impossible.
The Australian study tried to get around that by simply asking women what they drank during pregnancy, and found that the children of women who drank lightly during pregnancy had less behavioral problems and higher IQs than the children of women who totally abstained from drinking. This doesn't mean that light drinking makes your baby smart -- it probably means that in Australia, women who have better resources (more money, older, more educated) are likely to have a glass of wine every now and then during pregnancy. But it also didn't indicate that it found problems from light drinking.
I actually have yet to see a well-designed study showing that very light drinking during pregnancy is harmful. I'm planning to do the same thing I did in my last pregnancy, which is to abstain completely in the first trimester, and then starting at 20 weeks or so, have a small half-glass of wine once or twice a week if I feel like it.
I've already had to cut waaaay back on caffeine because I get crazy insomnia from really small amounts of coffee, which was the most infuriating thing, because I love coffee so much and if I had my way, I'd drink it all day long. Now I get one, maybe two cups of tea a day, and none after 10:30 a.m., or I'm awake for two hours that night. Sucksville.