I'm not sure on this. It probably depends on the volume of the security and the brokerage filling the order. When I've traded odd lots, I've often found the order broken into different trades unless I used a limit order (and even then occasionally different prices). Hard to prove one way or the other, especially since odd lots have only recently even been counted in trade volume. Regardless, large share price makes it harder for those with less equity to trade, and probably lowers the amount that those smaller investors are able to buy. For instance, were AAPL at $700, an investor with $1000 would only be able to buy one share, and an investor with $500 wouldn't be able to buy at all, unless they found someone willing to sell a fractional share, which is near impossible outside of dividend reinvestment. As for the index, you'll get no argument here that the Dow is a rather arcane measure with the oddity of share price having an effect on the security's representation. But, there are ETF's and Index Funds that invest in the Dow, so any listing in a new index means an automatic purchase of AAPL if they are listed, which they really should be with the Dow's supposing to represent the largest US companies in different industries.
Agreed again. I know people who have had success gambling as well, making enormous sums of money. That doesn't mean it's a good investment, and over time they'll return to the mean, as will short-term traders.