Thanks for helping me with the first issue. My question here is:
How do I lock down an object so that it can't be selected, moved, or modified in any way? I've watched the videos but there's been no mention of that feature yet AFAICT.
In object tab of properties editor goto the visibility panel and uncheck selectable. Another way to do it is in the outliner click the funnel icon on the header then click the arrow head icon. Now next to each object/collection in the outliner is an arrow head icon. Click that icon to toggle on/off selectibility. Note: Making a collection unselectable makes everything in the collection unselectable. Unless the object is in multiple collections and at least one of those collections is selectable.
As for locking movement(Location), Scale, and rotation you can click the Lock icons to the right of the transform axis. This can be found on the n-panel(Technically called the sidebar) by pressing N to bring up the n-panel and then click item tab. This can also be accessed thru properties editor->Object tab->Transform panel. Note: These locks won't really apply if you mark the object unselectable. Since you can't select it to move/rotate/scale it.
Thanks Dwayne, I didn't even think about the numbers panel even though it was one of the first things that I noticed when I started the tutorials. Duuuuhhhh! Please be patient with my ignorance.