All 3 may request KYC from any user at any time, typically triggered by an automated flag system. That's the stupid thing about it.
Yes they
May but not always, basing on how
"clean" his coins are.
Alternatively, he can exchange the USDC for USDT via any of those AMM platforms and then use P2P exchanges to buy Bitcoin using the USDT
1. Localcoinswap (He can even exchange USDC directly for BTC)
2. HodlHodl