Though some folks like to have separate threads for WIP and completed builds, more often they are combined.
My first dozen threads were of completed builds, most of which also had in progress shots.
Even in the group builds, folks tend to post their in progress shots, as it makes for less jumping around. There have been occasions I've had a separate thread for 'extra' photos, say for a complete walk around... Or maybe a deep dive on a technique or something.
I believe there there is a 10 pic limit per post. If you have more, just post again in the same thread.
How much text you want accompanying the pics is entirely up to you. Personally, I find some commentary interesting to read, and it gives opportunities to interact on related topics.
When I worked in museum exhibitry, additional text was always seen as optional, tailored to viewers who wanted to know more. Others might just ignore it.
On the subject of thumbnails, my impression is that a lot of folks would rather have the full-size image right from the get go, it makes for a more fluid reading experience. They can always click on the image to view all the images of the post together.
So yes, there are many ways to approach posting... And in the end, all the posted images are collected in the Media section, where it is possible to create 'albums', though that option doesn't seem very popular.
Not sure what you mean by "under glass".