I use an insulated FP because the glass ones would break after a year or so of just standard use. The insulated metal one I’ve had is going on 13 years now. I have only recently had to replace the plunger, as it wore out and was allowing grinds to pass on the side.
Stop plunging? When it bottoms out, everything I’ve read says when it bottoms out. The insulated one was on sale, and I can’t remember ever seeing a regular metal french press. I have thrown mine in the dishwasher. I usually just rinse it, or quick hand wash it, but I’ve tossed it in the dishwasher plenty.