12 GB RAM should be fine for Premiere Elements. Depending upon the rest of your system and what file type and codec you are editing, you may get away with less or may want more.
Hi - Will it help to have more RAM, so it renders quicker or more RAM would not make any difference. I am planning to buy a new Imac and it will primarily used for photo and video editing (personal use). I would like to get enough RAM and hard drive so I have no regret in 1-2 years from now. Thanks.
When in doubt, fill it with all of the RAM that will fit.
Processor speed and drive setup will most likely affect render as well as export more than RAM.