You want your GTC order parked on-exchange, not sitting on a broker's private book. Find a better (more expensive) broker.
I thought the real market also has circuit breakers in place. If the market falls X% too quickly, trading is halted for some amount of time.
That applies to the whole market, not necessarily a single stock.
It definitely can apply to single stocks, depending on the exchange. For example I believe NYSE has single-stock circuit breakers that kick in around 15%, then subsequent further breakers once trading resumes.