Probably no response because your questions sound too technical and difficulty to answer directly.
But i'll help and start you off with regards to your query on RAM/VRAM.
Different altcoins have different POW algorithms. For ETH's ethash, yes it does require a lot more VRAM and mining hash rate will increase the better your card is.
Mining does not require much RAM and 4GB or 8GB should be enough for even up to a 12 GPU mining rig.
There are lots of guides online that might help get you started then feel free to come back and ask more specific questions.
Thank you for the reply.
