Lance Armstrong in his glory days was measured at about 550 watts mechanical power output in endurance mode ; professional cyclists often reach 500... and they can do that for hours. That's 2/3 horsepower, exceptional for a human, especially if you compare the size of a cyclist to the size of a horse ! So those guys do about 9 W/kg.
A fit adult will do about 250 watts endurance for a few hours, 1 kW sprint for 1 minute. Those were about my figures for last summer on the bike. Since I weigh a lot more than a pro cyclist I had about 2.5 W/kg.
An adult bureaucrat will do about 80 watts endurance for a short time, this corresponds to fast walking, most people will start to breathe strong at this level, let's just say modern lifestyle and all-car society really turned us into wimps
If you want to measure your power, no need for fancy equipment, just time your ascent on a known altitude difference. E=mgh, P=E/T
With generator efficiency, if you're in the "fit adult" category you'll get maybe 200W electrical power, of course it makes absolutely no sense to do that as an electrical powerplant (and the electricity generated would be prohibitively expensive), but it would be fun !
At this power output your body (which is very inefficient) will burn about 600W as heat, so you will sweat insanely. If you do indoor cycling without a fan blowing a LOT of air (not too warm) in your face you'll be limited by body temperature (ie you will faint) not by your endurance ! Incidentally the fan would use quite a lot of power ...
Charge batteries with the bike, and power the TV with them, makes the "couch potato" moments a lot more deserved ! lol.
As for the iphone link, here's an idea :
Free2move Bluetooth Serial Port Plug: Amazon.fr: High-tech
your microcontroller can probably speak RS232, so if your iphone can associate with a bluetooth serial port you can easily make them communicate, without knowing anything about bluetooth protocol. You'll need to rip out the MAX232 in the serial port dongle to get a uC-friendly voltage.