Adding photos into RW8

Joanna,
I’m not at my Mac right now, and I’m no expert on styled text as I really never use it.
As for Engineer putting the sidebar at the bottom, I think you do have some control over that in the master style settings.
Engineer is based on Bootstrap 4’s 12 grid column system. So in master styles you will see to sliders to set the number “grid units” to use for main content and sidebar.
The way this works is once the total reaches 12 the next section will move down.
So simple set the “main content to a number like 8 and the sidebar to 4(as long as they total to 12) and the sidebar should move up to the side. Now on mobile it might still move back to the bottom (not at a Mac so can’t test this.
Take a look at the screenshot in this post:

Not sure if this would be the best approach (placing (images on the sidebar) since I don’t know what exactly you are looking for.

For the most part you simply hit the publishing button again. RapidWeaver is pretty good at keeping track of what changed and publishes the changes. Sometimes you may need to select publish all pages, but again pretty simple.
RapidWeaver will not and should not ever delete anything from your hosted site. Depending on who you’re hosting with, most have a file manager similar to finder to manually delete pages.