Those are giood ways to edit art, but you don't have to go to the HTML if it makes you uncomfortable (some are less comfortable than others). When you're in the edit window, just click on the art and the original dialogue box comes up, the one from when you first uploaded it, which includes the size box. Change the numbers there to anything that fits your layout.
I use 150 as a width and flush left (or flush right) when I'm saving space, but you can't see much.
I use 250 and flush left (or flush right) when I'm embedding art in a post.
I use 500 or 600 when I want the art to run the width of the copy (usually to accommodate a cutline and/or art credit), and leave the default setting that forces type to jump below it. Flush center achieves this as well, but I've never tested to see how that works on phones.
Sometimes a post is briefly visible but disappears when its page finishes loading. I don't know why this happens, but if you hit "escape" while the post is visible you can sometimes interrupt the process before the post disappears.
This post displaced the thread All-purpose newspaper strips discussion line from the homepage.
I had a problem that text I was trying to place after adjacent images in a post kept appearing between them. I found advice online to place the instruction <p style="clear: left;"> in the html after the images, and that solved it.