Re: Picture size question
I often use 640 X 480 pixels but the camera I use now takes photos with with a wide aspect ratio (16:9). I usually scale these to a nominal 700 pixels wide. The height then turns out at 393 pixels proportionally. An odd figure but it doesn't really matter.
If a photo is shown full-size in a post, the forum scales it down to 675 pixels wide (according to Firefox image info.) This doesn't seem to affect anything though.
A throwback to when dial-up connections were the norm:
My images don't normally go above a couple of hundred kilobytes in file size. This comes from having to keep file sizes low so that images loaded fast in a web page. Maybe not so necessary these days in view of faster Internet connections but old habits die hard.