i switched to the TRex bulb in mid january. i just raised the light dome to 15 inches, putting the bulb at about 16 inches. prior to that it was approx 1.5 inched lower.
as for the question about the second scute, i am not sure which one you are talking about (new owner still learning here). in which picture do you reference (1st, 2nd or 3rd)? and then do you mean to the left of center or right? all parts of her shell are hard.
not to make light of this but her shell looks like a one year old Earl Shieb paint job. i.e. chipped paint flakes