Hello Sergio,
1. Unigui use Sencha Extended JS Framework.
Sencha Extended JS use a special alignment (client side) : You have to use now Hbox VBox with Flex.
I think you might be interested in looking at Layout: advanced tutorial.
http://forums.unigui.com/index.php?/topic/7848-layout-advanced-tutorial/&do=findComment&comment=48504
Download the attached file : Layout_Exemple.7z and you will understand
2. Converting Forms in Frames, in my humble opinion, this in not good because all logic will change.
cheers