i have $50,000 in an account with ig for trading futures/forex/commodities. i am thinking of changing to IB, but i am interested in

a)if i trade with IB, am i actually trading the SPI contract or the AUD/USD spot, or is it similar to ig where they just make the market?

b) what are the transaction costs of trading 1 SPI december contract/audusd contract /gold contract and what is the usual spread?

c)does IB offer mini contracts similar to IG?

d)what is the funding rate charged? +-2% over RBA?

does everyone also recommend that IB is the best platform from which to trade US shares. if so, do they offer conditional orders (eg. buy GOOG if last price is lower or equel to 360 down to 350)

thanks for helping.