If u are a profitable and active trader, u do need at least 10K account for deposit. Otherwise, the commission u pay would be quite high.
Very adventurous types could still open multiple accounts and keep trading huge amounts with extreme leverage.
I don't think you will have any problems getting up to 100:1 leverage for the amounts you mention. certainly 50:1. Above that you have to negotiate with the PB. You can get 100:1+ leverage up to 500:1 if you are willing to trade through a dealer. In terms of MTF's/ETNs I believe leverage tops out at 100:1
I suggest the leverage should not exceed 1:100, it's maximum leverage provide by bank for brokers, also it's for the consideration of risk control.
Certainly with larger fund accounts, brokers never offer higher leverage, because they are MM. I see most broker only offer maximum < 1:500 for VIP account, my broker is 1:200 (check out at this link https://goo.gl/BvxAJ1)
it is up to a trader what leverage he likes to use. I think 1:50 leverage is less he should have a large amount in his trading account for this. I like to trade with 1:100 or 1:200 leverage in trading . If you had good skill you can use high leverage in safe way it will support you to get profits . Without experience high leverage becomes a killer .