Firstly, do not hijack someone else's thread with your own questions. I have moved your post into its own thread.
Dumb questions, please tolerate my ignorance: Q: are the private keys stored in nodes hard drives/wallet files?
Not all nodes have wallets, and not all wallets are nodes. It doesn't matter where a wallet stores the private keys, it just needs to be able to access them somehow. Most desktop wallets store the private keys in wallet files locally on the hard drive.
Q: can someone use any data from blockchain or nodes wallet files somehow to use the data in key collision attempts?
This question doesn't make any sense.
Q: last one, what happens if I remove the ticks for all kinds of files and folders in the index configuration of my windows machine and run Core wallet as well? does that in any way effects the performance of my Core wallet as to creating any issues for proper syncing?
That indexing is for the file search service, nothing to do with operation of anything else on your computer.
