Gr33n,
If you want to have both a avatar field and a picture field, just follow the instructions I gave in response to your last question in this thread. It will not be a drop down box, it will be a slot for people to enter the addy of the image.
No, I don't know a way to limit the file size (in MB) but if you set the diminsions of the image at a reasonably small size, you should not have problems with download times.
