Welcome to TL!
I know thinkorswim.com gives you the trading platform, reasonable charts and indicators, demo account...but they don't have a backtesting setup. As for something that's free that will give you backtesting.......I'm lost on an answer unfortunately. I know TradeStation is like the king in backtesting and coding worlds. I personally use InvestorR/T from linnsoft.com and love them, but they aren't a brokerage. Just charting with custom indicator possibilities as well as backtesting performance of trading systems.
And for YM, you've come to no better place than TL! Lots of YM traders and the founder, SoulTrader, is one of the best YM traders around
Welcome!