Macs..
a. NO. Good spreads but the platforms for online are not the best. Fins have a great live feed that stops requotes ie, the price is streaming as you click. Cantor the most secure from global size and products offered but less cool on the spreads.
b. yes, the percentages very from company to company, its all in the small print
c. yes. You just pick your position for entry level,price and buy or sell. ie. I want to buy the FTSE at 5550 or sell it at 5499, (it will be activated when the relavent price is triggered). Then place an order (click the order box online or phone the trade)