For attaching pics they need to be no more than 25 k, however you can increase the actual size of the picture by reducing the quality if you are using a program such as photoshop. Better yet, upload your pics to your gallery on sSnakeS.com and have your pics hosted from there. You can use larger pics, as well as post mulitple pics in your posts, whereas attachments only allow one
As for the cage question, a 30 long is fine for most balls. Hard to see in the pic, but it looks like yours is a 30 tall? I'm not sure what the floor space is on those. Generally you want to give your snake 1 square foot of floor space per foot of snake