Cheapest Broker for Options, FX, US Indices, Gold

Beginner Options Trader looking for best options broker for Australian residents.
Are there any negative tax implications if I use a US or international Broker?
Intending about 10 small trades a month, high return, high risk NTM options.
Options will have daily, weekly or monthly expiries.
I would need a demo account for practice.
Is IB the best choice?
Starting Bank is about 10K

thanks

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