Re: solid foods before 6 mths?
It's not so much that the recommendation to start cereal to make baby sleep at night is unpopular, it's that the research says otherwise. This advice is so common they decided to do research studies on whether or not it helps, and the conclusion was that it does not help babies sleep through the night. It's possible your baby just decided to sleep about the same time you tried the cereal. Babies go through cycles where they suddenly start sleeping longer, and vice versa.
Also, some of the most recent research about solids is that starting this early can increase the risk of type 1 diabetes, not to mention allergies. Babies are designed to wake often. The medical definition of 'sleeping through the night' is 5-6 hours, not the 9-10 adults are accustomed to. Here are some links (nonLLL, but reliable) with information about the studies:
http://www.kellymom.com/nutrition/so...-diabetes.html describes some of the risks of starting solids before baby is ready.
http://www.kellymom.com/nutrition/so...ids-sleep.html describes the research and other evidence regarding giving formula or solids to make baby sleep at night. Lots of information about both issues in this article.
Both of these links also list the studies that I can never seem to keep track of myself. It is important to do all the research on any topic and then make the decision that fits your family best.