Forget the air pumps, they would only work for one bag.
Forget the heater coolers.
Use a chilly pak if it's too hot, or a coke bottle filled with hot water.
Surround either way of heating/cooling with a newspaper, as direct contact with a bag can move the temp. drastically.
Both cases, keep the lid on.
Enquire at the shop where you buy them if they have oxy, and have them use that for the fish.
Pack in small numbers per bag. Especially cichlids.
One per bag, as they are liable to fight kill one and the other will die from pollution.
Caryl's suggestion of water from home is a good one.
Get spare plastic bags and a supply of rubber bands as well.
Make sure your tanks are ready at home, as it is a super tedious job after a long trip and you'll be tempted to do shortcuts that can be deadly.
Oh.
Take a good book for the missus to read while you're in the fish-shops and make sure your wallet is full of greenies, and/or make sure your credit card isn't max'd out.
Good luck
Happy shopping.
Alan 104