Any research/numbers on correlation between age of mother @ birth, and birth defects in children? Trying to find some hard data. Thank you!

See the CDC webpage. http://www.cdc.gov/ncbddd/birthdefects/index.html is the centers for disease control webpage for birth defects, where you will find excellent epidemiologic data and interpretation. As a general rule, women who are older than 35 have an higher risk to bear a child with a birth defect because of a chromosomal imbalance. However, we have become adept at managing these risks. Your OB can explain more.
Yes. I have not looked at the recent numbers, however, there has been a known fact that the older a woman is when pregnant beyond 35 the more likely a child could be more with the defect of being mongoloid.