Yeah the code you've mentioned is the standard for posting images within a comment. What annoys me is the text in square brackets is merely used for disability apps - I would like it to pop up as alt-text also, like in an xkcd comic. But yeah you don't actually need to put anything inside the square brackets. If you look at the source of my comment above, it only has the link in the round brackets. This is what happens now when you simply past an image into the comment box, it uploads to your instance and generates the link automagically.

With regards to the auto-expand function, I also don't completely like it, as I said in the OP. On old reddit there was an extension called Reddit Enhancement Suite (RES), which added a bunch of extra features and buttons. One button was "Show Images", which would expand all images and gifs (not videos that might have sound) that you had on the page. The button would then change to "Hide Images", which would contract them. This is the best functionality, imo, as it gives you full choice. But if I have to choose one default and manually change, like lemmy makes you, I'd prefer auto-expand, as I don't like having to click every image to expand it - I just want to scroll down a page, view some memes, and open news links and comment links in the background to read when I feel like.

I also use an extension that makes opening links a lot easier. If I hold right click a link and drag down, it opens in the background; if I hold right click and drag up, it opens in the foreground. I use the background one extensively to queue up a bunch of tabs to read, as I scroll through some memes and whatnot until I want to view something in depth, then start going through the tabs.