Reply to Traktor collection on external drive, questions!

So here's the thing: my computer and Vestax VCI-400 EGE got stolen, but luckily I made a time machine backup before the incident. So now I'll be borrowing a Macbook Air while I'm waiting for my retina Macbook Pro, but my issue now is storage, so now I see no other option but to store my iTunes and Traktor collection on a external drive!

So tell me:

1. If i rellocate my iTunes library to an external drive, will I be forced to rellocate all my tracks one by one if my external drive would somehow dissconnect or can you select an entire folder to rellocate an entire collection?

2. Will my stripes and ID3 tags from my previous computer (which I will import to my new one) still apply to my traktor collection even if they are now going to be located on an external drive instead of an internal?

3. Does it suffice to "DJ" live from an external drive (stability? reliability?) and IF your drive got disconnected, did you have to go through the procedure as asked on question 1.

4. Should I go for powered or non-powered Hdd's when performing live and what brand is most widely used among performing DJ's?

Thanks in advance!