What's the best/safest way to handle likely bottle bombs?

If you want to stop carbonation, you can pasteurize the bottles. To do this, use a pot of 170 degree water and immerse bottles. Let temp get to 170 again, and let sit for 15 minutes. Not sure how this will impact the taste of the beer, but I've done this for cider.

As Thomas answered, safety is paramount right now. Glass shrapnel is a serious reality, and you don't want that in your eyes, hands, face, anywhere. Wear gloves, wear glasses, I'd even recommend a jacket/sweater when venting to keep shrapnel out of your arms/torso. Keep your beer as cold as possible to slow down fermentation.

Store them away from anything that could be damaged by them exploding. Your cooler that you have them in is probably ideal, as a bomb at most will just cover the rest of the bottles in beer. While they are thick bottles, there's no telling how much pressure they are under, so move them outside in the cooler, don't carry them out individually.

Depending on whether the beer is infected, it may even be salvageable. As Thomas said, get them chilled down before venting. The weak point is the cap. Whenever you go to handle them, wear thick gloves and hold them by the top to cut down on potential shrapnel spread. When going to vent them, cover the bottle cap with one hand to prevent shrapnel from shooting everywhere, while using your other gloved hand to pop the swing top. If it's going to explode, this is most likely the time it will happen.

If the beer isn't infected, keep a few sanitized bottles, and a sanitized funnel readily available, as you may be able to salvage the beer with a bit of oxidation as the cost. When they're that carbonated, they should keep in bottles. If they're infected, toss them.

These are very thick bottles. While I wouldn't let them pressurize forever, if you keep them cold, wear leather work gloves, and bring them outside in a bucket of ice water, you should be able to open them safely (and messily). I also recommend using safety glasses.

For safety (and cleanliness) reasons, I wouldn't try to save them. You might be ok if you can vent them without any gushing, but this depends on the reason for gushing. Were they infected or did you add too much sugar? More information is needed to tell you to save the beer, so my answer is to stay safe and get rid of the beer.

It's not possible to say how likely these are to explode or swing open on you during movement. I'd say unlikely at this time. If they do blow, chances are good they'll either just open or break where the metal top attaches to the glass (this will be a weak point). Again, wear gloves and put them in an ice bath to open/vent.