The important difference is that the one bill is to ADD yet another new tax on us (and lawmakers love those), while the other bill is to REPEAL the income tax (lawmakers hate repealing any tax) to replace it with state run sales taxes.
That's why, in this case, we need to e-mail / contact...
Zenfire is usually not free unless your broker is just charging you a heck of a lot for commissions. Most brokers will instead charge a separate "technology" platform fee, but have much lower commissions.
Depends on your time frame of trading. Futures give you more leverage, but that leverage can also wipe you out. So if starting, trade small and with little or no leverage, IMHO.
Pretty standard. I'd say watch your broker and your trade statements like a hawk so you can catch any mistakes early, and so hopefully never have a reason to go to arbitration.