Does it make a difference?

No difference.

Always. I open the windows and let the interior cool down while driving for a minute or so before turning on the a/c. It is what my Dad tought me and makes sense to give your compressor less of a load than fighting 120 plus temps in the cab.Less drag on the engine when warming up also....of course there is no way to prove this either way. Just common sense....haven't had to replace a compressor on my last two trucks.Knock on wood....

I start up the car, roll down the windows, get organized and turn on the ac once I am out of the neighborhood.

I hit the remote start and hope it's a cool 65 by the time I get in.

theres a clutch on the ac compressor that cycles the ac on/off.. it makes no difference when you start the vehicle with it on. only thing that will help is make sure you are NOT in recirc mode when you start... that pulls air from inside your car to cool off- usually the air outside the car is cooler than inside... give it a few minutes before switching to recirc.

This is the truth! Cousin told me about this several years ago and what a difference it makes. Regular A/C for about 2-3 min and then switch to recirc. Cab temp cools down much faster this way.

Don't know if it does. But I always do, just in case. Knock on wood, no problems.

does not matter to me but i drive diesel.

I have heard that if you leave the selector in the off position you will have less of a problem with fog on the inside of the windows.

having the a/c off when you start your vehicle also makes less load on the battery when you start it so it cranks a lil easier, usually not enough difference to be able to tell though

When you start the engine, there is a huge voltage drop to all the accessories, which can cause overheating in the fan motor and the AC clutch to slip when the engine starts. Won't hurt it much each time, but the the times add up till a failure happens.
On some engines (Ford Power Strokes) the alternator doesn't start for a few seconds, and the voltage is low for a while. Ford puts a warning sticker on the drivers sun visor not to have lights or AC on when starting.