Switching from Testnet to Mainnet and back with CNTOOLS

Hi Everybody, I am a bit of a nooob, but have managed to get my Cardano Node set up on AWS using CNTOOLS and with mainnet. I see instructions for switching to testnet involve downloading new prereqs.sh with -n extension. A couple of questions:

  1. Does mainnet node data stay in place if I switch to testnet and/or keep syncing? It took a long time to sync in the first place and I wonder if I can toggle back and forth between mainnet and testnet easily enough, or should I create a new instance in AWS to run testnet?

2, I am using Lightsail in AWS, and I chose the 4 vCPU, 16 GB Ram option, which used a lot of resources while initially syncing the mainnet node (which is why it took so long). Does the testnet sync faster, and use less resources? This question is so I can start a cheaper testnet instance if the answer to Q1 is that switching between the two is inefficient.

  1. Is anyone else using Lightsail, and is 4 vCPU/16GB good enough for ongoing node operation once initial sync is done?