Too confused!!!

So far, you seem to be able to basically move the old base, slap the new one down in position of the old base and use the same decorations for the %. The only reasons right now to keep decorating the old base would be if you want to continue to send characters on jobs there, or if you just want to make it look good. Not sure whether the third act will mean anything different, but it looks like there will be a third base to reinforce. For now, though, you only need the reinforcements on the base where you are sending your characters.