megan, pin head crickets arent agressive and are sometimes used as a main staple in diet. normal crickets do have mandibles and are capable of pinching the newt (inside or out).
everman, i do suggest separating them during feeding. if you have a special feeding tank for both of them, you keep the main tank clean, and you can be sure of how much each has eaten. and a newt can only eat what the owner feeds it. if you're worried its eating too much, DONT FEED IT SO MUCH. if you put less food in there, it obviously cant eat as much. the enlarged gut doesnt sound like bloat, just like you're overfeeding. follow the recommended guidelines. and remember: newts can go sometimes a few months without food. they dont need to be fed every day. just like houseplants: if you water (feed) them every day, it has adverse affects.
also: wax worms are very fatty, and should be used as a special treat, not as main part of diet.