Can it be done? Or is it hard to do it? Aside from the jab which can keep a shorter fighter at bay, do you think weaving against them is advisable?
Yeah, it's bobbing vs a shorter opponent that could get you in trouble. In fact, you can watch some of 6'-9" Vitali Klitchko's fight and see that a large percentage of his defensive style was weaving away from shorter opponents. I wouldn't suggest weaving too often though, especially with your hands down like he did although he got away with doing that.
well byrd was firing shots like a turkey shoot that last round because he was moving his head back and fourth.
Depends on how much shorter he is. If it's only by a few inches then it shouldn't be that much of a problem.
Every fighter should know how to bob and weave. Lennox Lewis would do it occasionally against smaller opponents. Nevertheless, if you are taller than your opponent, it tends to be safer for you to fight tall.
If you're straight up and your opponent is aiming punches where your head is... then it is always advisable to bob and weave a bit to avoid his shots, no matter what height he is. It's always better to get under shots than to pull away from them.