My brokerage firm is Scottrade, no limitations except a waiting period for stocks selling under $4, depending on how you fund the account. Same day for wire transfers, 3 days for other methods. If your current firm doesn't offer trading MSLP, transfer a portion to another brokerage firm. Not advice, just a suggestion
As far as opening another account: A guy needs several different money accounts.
One for investing, one for living expenses, one for retirement, and one for gambling and drinking with your friends that the wife doesn't know about.