I want to buy the new iMac with a VESA adapter on the back. 1. How difficult is it to open and swap out the RAM? 2. Is there any real chance of damaging the screen or unit by opening and closing it? 3. If I want to buy it with the baseline amount of RAM, 8GB, would I just take that stick out and replace it with say two 16GB sticks, or what is the best way to configure it when purchasing it to save the most money by doing the RAM upgrade myself? Thanks in advance.