1.
1276 x 902 and 200kb
It may not be good enough for all you pros but it uploads just fine and very fast using the Quick Gallery Creator
The old "Attach an Image" button is pretty limited (and obsolete)
There is also a difference in image size and file size many people do not understand but if you like hosting and linking to a 3rd party account somewhere by all means go ahead, just for the record though it isnt necessary simply because the gallery creator works great...