You might have exemplified quite a lot in the OP but, I find you trying to make the same point. Just having to repeat them severally but, all saying the same exact thing and that is;
Being a huge Bitcoin hodler and suddenly decides to cash in fiat for most or all of your hodlings rather suddenly. Either of your hodlings or deposit on the account from a wallet.
Well, I don’t think of that yo be much of a problem. Like it’s generally known, there isn’t any restrictions to the deposit amount except a minimum deposit amount but, there are restrictions on what volume that can be sold on the exchange, mainly based on what volume buyers are advertising to buy, other restrictions are due to your level of verification.
Most CEX operates a KYC system and as such, they leverage your level of verification. A good knowledge of this would put you in the best position on how to go about trading your coin on CEX.
Mind you, it’s better you understand what is said in there T&C to avoid the situation rather than finding solution when your in the solution.