Hi Fred, and welcome to the forum.
The name is Sagrada Familia and not the way you wrote it.
https://en.wikipedia.org/wiki/Sagrada_Fam%C3%ADliaI only watched your first slides.
You should consider styles and/or other methods to cover the whole area of the screen, and not leave so much black around your pictures.
Transitions should be used with a purpose. Either you want to make an interesting break in your show, or you want to create interesting effects with your pictures.
It all depends on what you, personally, want to convey in your show.