Interesting that the size of the ice is not mentioned. I find large pieces of ice to be ideal as they cool the drink for longer yet don't overly water down the drink due to less surface area melting off.

Also, I HATE when bartenders add too little ice to shaken drinks and end up shaking it to oblivion. Makes me not want to order drinks from that particular bar.

It does make a difference. The big rock ice is great for whiskey and scotch the reason you mentioned; keeps it cold with minimal dilution. Crushed ice is great when you want dilution, like in a mint julep. It really depends on the style of cocktail and personal preference.