There are plenty of other aftermarket stereos with Bluetooth linking to the iPhone. The iPhone should link automatically every time the unit is powered on, with these units. There are also device interface's that will let you hook up your steering wheel controls to most aftermarket stereos, as long as the stereo has that capability built in. The easiest way to get advice on this would be to call Crutchfield. You don't necessarily have to buy from them, you can just take their advice, and buy elsewhere. I found that Amazon usually has lower prices than Crutchfield on most units.
BTW - February is the best month for buying this sort of stuff, since the new models are released at CES, which just wrapped up. You can get a good deal on last years models, which are usually no different on features, they just update the looks.