Re: Cant paste pic from Ai to AE as a mask

it doesn't mattter whether the design came from a pen or a trace. you should be able to use the paths that trace creates after "expand" of the trace. the paste into a shape layer or a solid in AFX will have anchor points and paths, that's what you're pasting. twirl down the masks menu and you'll see the component paths there. a design like yours will no doubt have lots of component parts, it wont be a single element and it will have all the anchor points and paths from illustrator. you can select in the stroke plug-in which paths the stroke effect uses or it can use them all.

you mentioned an AISC option, don't know what that is but maybe double check your preferences on the illustrator save panel and check PDF compatible, and maybe double check your general prefs under file handling and clipboard and ensure that PDF and AICB are both checked.