The laptop came with 8GB and I added another 16GB (I want/need to be able to run a lot of Docker containers in Kubernetes, so the extra RAM is important to me). I don't think it is necessary for general use.
Sound works through the speakers. I followed "standard" guides and inject "3" (config.plis ➔ Devices ➔ audio). I have sound through the speakers and over HDMI but not through the headphone socket. I would like to get that working again. It used to work but got broken along the way. I think it was when I followed RehabMan's guide and used the utility that installs AMLs and Kexts, etc. That got the backlight, power control and volume buttons working, but I think that's when the headphone socket failed.
I am now trying to make the laptop more secure - it has to be lockable and the disc needs to be encrypted.