It only takes bravery to make a hero..
Sorry for the crappy image..what is the best size to post on the boards??
I also assume that after posting the post can not be deleted??
I always post 600, it's an agreeable size. No you can't delete it but you can modify it, so put in another picture.
Also you can have dynamic tags on the images, above I've made one larger and one smaller, if you hit the "quote" button you can see where I've changed the size. It's best used to downsize rather than up because of resolution -as you can see.