Few small questions about locating Macbook air specification information

Hi

Sorry for silly questions but I'm a bit stuck after trying to find the answers myself...

1. I went to About this Mac > System Report > Hardware. I cannot find the RAM but does this fall under Memory?

2. I went to Finder, then Capacity is showing 121GB. Is the the correct location to check the size of the Hard Drive?

3. Where can I check if the hard drive is SSD or not or a SuperDrive?

4. I needed to find the Model Number which I couldn't find using 'System Report'. Can you please let me know for future reference where to Model Number on the actual machine? I did actually googled the serial number and found a website with the specification of the machine, but is this good practice and normal way of finding out this information?

Thank you in advance for your help.