Yes the rhp heats the ground and inside the hide as well. As far as hot glue I don't know. I've always used suction cups for the probe. I wouldn't recommend putting hot glue on the rhp. The probe doesn't go directly on the rhp. The rhp comes with screws that u screw into the enclosure. I've heard of people useing hot glue in their enclosure but I've never done it. All the plants I've got came with suction cups for hanging. I think gluing them in would make it harder to take out for cleaning.
The suction cups that come wit the plants don't stick to the PVC walls :( so maybe ill just use some stock on hooks or something like that