4. Any constraints when submitting an order?

For LMT orders, there is a minimum order size in notional terms. Currently it is set to be $0.5.

The calculation of order notional is driven by the price and quantity as of the submission time.

For latest minimum order setting, you could retrieve from: http://dboe.exchange:8686/api/query/clobSpecs

{
  "taker_fee_bps": 25,
  "chain": "AVAX",
  "maker_fee_bps": 5,
  "num_px_level": 6,
  "max_order_validity_sec": 3600,
  "max_ref_px_waiting_sec": 600,
  "ref_px_update_random_chance": 10,
  "ob_address": "0x6751b76eF043bf221ee129927A115e9e5a09b212",
  "min_ref_px_waiting_sec": 480,
  "min_lmt_order_notional": 100000000000000000000
}