1- is there a significant difference between a pair of glasses and an artificial retina, or between an artificial hip and a lower-extremity exoskeleton?

no there both have always been there in theory for a long time. its always been there but now its is becoming "more organic" by merging it into the body.

2- what are the potential benefits and risks of advanced bionic devices containing embedded microprocessors?
there are many benefits, like help people that have lost their sight, or for people that have lost their hand etc, also in can better human life like make us stronger, or carry heavier things, like the firefighter who can carry a heavier load to save more people etc. it can be a bad thing, of course, if its used in the wrong ways, in violence, and in hate. also it can make us dependant of these sources of strength.

3- if advanced bionic devices are conceivable do you think their development is inevitable?
i think now that its actually possible to create types of machinery, then fore SURE it will be invented, i wont be surprised that in the next couple decades, people will be switching their legs for robotic legs....maybe not that extreme but it will be used!