so I looked at your questions and tried to keep it short.
no there must be nothing in between, please apply ointment regularly on the places where the belt is sitting
like Laura said my-steele can be a little bit adjusted. if your daughter tends to weight fluctuations, you must call the manufacturer or write what is possible.
i always have the secondary sign on it, i pee through the holes, is a big chaos in the beginning but you can learn it
when she gets her days she should tell you that, when blood comes, the belt has to be cleaned before she is closed again
you have to give very exact measurements, the belt has to be extremely tight only so it is safe, so take tape measure and measure your daughter
i have a version with a hole in the back. that's a problem when pooping, because you have to take care that the hole sits right otherwise there is a sour one. for safety but definitely the best variant.
to the questions 1-3 a short text. hygienic problems can be avoided by regular washing of the belt and your daughter.
for safety. it is possible to open any belt with tools, but it is impossible to put the belt back without you noticing something. so she can't trick you.