animated gif / png

I have a couple of questions that don't seem to have easy answers (or I'd just like some opinions):

1. Can .png images be animated? I like the idea of using non-proprietary formats.

2. Can .apng files be used as user images in LJ?

3. If you have some knowledge in this area, what software do you use to create animated .gifs / pngs / apngs under Linux?

Thanks in advance!