For the first part, you concern is a good point. The software can be used in a way to address your concern.
The underlying model builds a model based on time to event, and assumes the event duration is zero, or at least negligible while calculating time to the next event.
If your data has the situation that you described, you need to understand your options. The platform supports two formats: time-to-event format, and date format.
If you carefully calculate operation time, and remove maintenance duration, then use time-to-event format to analyze.
If you ignore maintenance duration, and use date timestamps directly to avoid detailed data cleaning work. That should be fine if maintenance duration is relatively short and infrequent during operation. Otherwise, you should use the previous approach.
For the second part. I don't understand the question. But the model itself does not make assumption on the type of maintenance. If the maintenance type is corrective (i.e. replace with new), then it is likely the beta of the fitted model is close to one.