I'm shortly getting an iPhone. From time to time I plan to use it as a personal hotspot with my laptop. (I'm going to be cautious about burning through my data)

The laptop has Bluetooth and wifi b/g.

Which is faster?
Which is easier? (I don't mind if it's fiddly to set up for the first time, as long as I don't have to dick around every time I want to use it.)
Which uses the most battery power from the phone?
Which is better security?
Is there anything else I need to think about?

Cheers,

Martin