Hi there, you do need these items for your water mixing, else you are going to exchanging qty's of cold water into a warm aquarium on water changes..If the water is not aereated, the pH balance will be off and possible that all salt wont of correctly dissolved..
Like i say, this does need to be done before you introduce this water for water changes...Likewise, this is just personal preference here, but i always make sure that my top-off water is the same as the tank temperature..
Niko