I read a good post about EFA, it covers many useful topics. ("19 important points you should know about iShares EFA before you buy it")
EFA ETF profile (i.e., what does it track?)
EFA underlying index
EFA number of holdings
EFA historical performance
EFA dividend yield
EFA expense ratio...
There are three reasons to buy IVV, first of all, it exposure to large, established U.S. companies; secondly, low cost; thirdly, long-term growth opportunities in your portfolio.
Hope this can help you.