I second everything Malcolm has said here. I tend to use the search facility all the time and I've never had problems with it. Occasionally some images have not been available but this is rare.
Yes the images themselves have quite rightly been copyrighted. they own the images and have gone to great lengths to make them available.
Transcriptions are absolutely in the public domain, but as Malcolm says, it is common practice and common curtesy that all transcriptions used are copied faithfully and are acknowledged in full reference. This also acknowledges the work of the original collectors like Harding who preserved them for us.