Any commodity futures brokerage company that you trade with will require that you read and fill out certain forms, and provide certain information before they will open a trading account for you. U.S. regulations require brokerage companies to inform potential clients of the possible financial risks involved in trading futures and options contracts. To open a trading account, you will need to read forms explaining these risks, and sign them stating that you understand and accept those risks. The reason for this is that your broker and his company will be liable for your losses if you do not cover them. However, they will seek as much information as they feel that they need to minimize that risk.
Different companies set margin requirements and deal with margin calls in slightly different ways.
While the futures Exchanges set the minimum levels for margin requirements, brokerage companies can either use Exchange minimums, or set their margin requirements at some higher level. Some companies also differentiate by having different margin requirements for hedgers and speculators. Commission costs will vary from company to company, depending largely upon the services they provide and their related cost structure. Commissions can also vary from customer to customer or over time if a firm uses volume discounts. Make sure that you understand the process the company uses.