No idea about how thick they are but you could try cutting up a plastic document holder/file. Like this one: http://www.amazon.com/C-Line-Biodegradable-Acid-Free-Loading-33747/dp/B004Q9Z9FW/ref=pd_sim_op_4?ie=UTF8&refRID=0FJAJFJAT6FGHWW7HF36
Food safe? You wouldn't want to eat it but if it is in contact with your cake for a few minutes while you smear royal icing over it, I personally wouldn't worry about it too much.
Neither, they are covered in fondant...but that does not go to say you couldn't do it in chocolate or poured fondant but you wouldn't get the same finish. Google "Temari Cakes" for more info...they are tricky beggars.
It's a good idea because it weeds out customers that think you will make them a dozen cupcakes for €12 and saves you a lot of unnecessary phone calls and emails.
Having said that, its a bad idea to sell anything with copyrighted characters on - it's against the law, unless you have permission from the copyright holder, or are using licensed plastic toppers and stuff from companies like Deco Pac.
You should advise her that most raffia shreds really badly and that she will end up with threads of the stuff all over her cake. Your call if she accepts that fact whether you want your name associated with a cake with papery inedible bits all over it.
It looks nice on Pinterest, but I am of the belief that 99% of cakes on Pinterest are not real and not used for real events!!
Depends when you want to eat it. If you want it ready for Christmas Day, I would put the fondant on on Christmas Eve. To do that, you would want to put the marzipan on 2 days before, on the 22nd. The marzipan needs to dry out a little before applying the fondant.
Is it this? http://www.cooks.com/recipe/hl9xb0ax/bible-cookies.html
That one you fold the cookie when hot so it would end up as 4 layers and in a fan shape...the filling would be a piece of paper with Bible verse on....not sure that is the kind of "filling" you had in mind?!