Re: A couple of noob questions about bitcoin core and miners
1 - Does ASIC machines get some sort of copy of Bitcoin Core to generate blocks, verify them, et, cetc?
The normal Bitcoin Core allows the user to solomine using their ASIC through getblocktemplate. It's not widely used by ASICs and mining pools as most of them utilise SPV mining, ASICBoost etc which means their backend is heavily customised and modified.
3 - If 1 is a "Yes", can I generate a block just for the fun of playing with it and learn about bitcoin core commands some more? Can I try to create a raw transcation put it in that block and try to add that block to the network, even knowing that obviously it will be rejected and probably I'm even thinking baout it the wrong way?
You can manually generate your own block (probably won't meet the target) and submit it. But the initial filtering by your client likely would see that your block doesn't meet the requirements and reject it in the first place. 4 - IF I can't do that on mainnet, can it be done in testnet or regtest for learning purposes?
Testnet has significantly lower difficulty so you can probably get away with a 1TH machine.