1) It depends. Higher-quality firms will want more money in order for you to get the lowest commission rates and access to the best technology. 2) Less desirable firms will take less money, cut back your leverage and not offer any perks.
http://www.infinityfutures.com/ Awesome customer service with low account requirements and fees. Somehow, they are also teamed up with the CME and offer tons of excellent and free educational webinars. Well worth looking into just for the webinars even if you don't trade thru them. Steve