You may want to have a look at "Ulead-Gif animator" they are the top of the line
and can do everthing you mentioned..and they are much more reliable and (almost )zero bugs then AVS
Ofcourse i should add that what AVS is trying to do is more complicated.
Anyway Ulead-gif animator can do:
Gif > Video,
Video > Gif.
Making a Gif from separate pics,
Maing separate pics from gifs
Add effects,titles,transparency...etc
.
AVS better stick to what they have right now..and clear up its overwhelming amount of bugs.
Now what AVS needs to add is an option to add a animated gif as an image...or as a video-overlay
currently you could do that...take a gif..convert it to video...add the video as overlay
that is way to much work and fails many times..because of restrictions in the overlay-editor
and a bad working chromakey that causes ugly looking gifs..the chromakey needs a "'Tolerance" setting also.