The programs are not blocked on the device and require no special modification to install.
^^ Other than installing untested, untrusted, code onto your phone. Pretty much the same as Jailbreaking an iPhone. Same amount of risk.
Not really. When you jailbreak the iPhone, you can brick it. That's a bit more risky than installing an app.
Yeah, if the app somehow was that bad a reset would take it out unlike a bricked iPhone which would simply stay useless.
Since the advent of DFU mode on iPhones it's basically impossible to brick it via Jailbreaking. Worst case you just have to restore the original firmware.
You still lost the warranty on your iPhone unless they don't catch you.
