An icecream tub will be fine. It really doesn't matter what kind of enclosure you hatch ootheca in, as long as there is enough room for the nymphs to hang down when they emerge, and for the nymphs to disperse, without crowding. Also...It may be an idea to not use substrate...I have used substrate in the past, at nymphs have got trapped, and wedged in it, and when taking the nymphs out, its awfully awkward as well.
But yea, looks good
Superglue will be fine for the ootheca, altho, try and use as little as possible...maybe just a dab on the the end.
yea looks like it might be hard to find all the mantids if they get amongst the moss, but i guess that doesnt matter much. also, are the holes in the mesh too big? hard to tell without size reference. (it's just you might want to put fruit flies in there)