1. When exchange rejects the order, what event we\u0027ll get? 2. How to get the latency of new order registration or cancel a placed order? 3. Is it possible to place a single order that contains multiple pairs of trade? (securities) e.g: - ETH/USDT, SELL 0.001 at 270$ - BTC/USDT, SELL 0.000001 at 8000$ - ... Put them all in one order.