A 1 lot.
No minimum for time to cancel or cancel fees. The cancel fees generally only effect traders using firms that primarily represent high volume, professional off floor traders with little or no retail customer base. Generally they are if the firm cancels more than 50% of their total orders, they are charged $.50-$.75 per cancel for all cancels. slk, and their varios JBOs, and branch offices are the only group I know for sure pass on these fees.
The fees were put into place to handicao large volume off floor traders and try to return the edge to the floor.