One picture with six photos in it travels better than six separate images, whether it is going into a message, a listing or a report.
Photos jammed edge to edge read as a mistake. A consistent gap, even a small one, makes the same set look arranged.
A white background suits almost everything and prints cleanly. A dark background makes bright photos pop but shows any dust or edge artefacts in them.
Each photo is cropped to a square to fill its cell, so nothing is stretched. Crop the important part into the middle beforehand if a particular photo matters.
Two across suits four photos in a square, and three across suits six or nine. The default of 2 and 800 pixels each gives a collage about 1,600 pixels wide, which is plenty for sharing. Raise the size of each photo if the collage will be printed.
Every photo is cropped from its centre to a square, so pick photos with the subject near the middle. Add all your photos first and then set the order with the arrows. A background of off white looks gentler than pure white, and black makes colours stand out.
As many as you like. Choose how many go across each row.
Yes. Each is cropped square to fit its cell, never stretched.
No.
Two across for four photos, and three across for six or nine. More than four across makes each photo small.