Sorry for the rather last answer~
1. I got mine of ebay back then, I fear the seller doesn't exist anymore through but give it a try
2. they were made of super light air-drying clay (paper based) - you should get that at a hobby shop or any other store selling art supplies. It is important that you have a lot of pics at hand to compare them to the original.
3. It is completely self made, the shirt is from a streching fabric which was rather hard to sew. The Hakama from a stiffer fabric which is close to synthetic linen. the black lines are a black velvet ribbon sewed on by hand.
4. sewing lol, I looked up sewing patterns on 'reglan shirt' and 'hakama' - there are a lot of those around online ^^ Like I said above, the black ribbon is hand sewn - everything else made with a sewing machine
5. I used wood as a base and some balls made form a paper material for the handle. If you haven't worked with wood yet and don't want to work a lot (a day up depending on how fast you get a grip on it) I would recommend getting a LARP sword instead and paint it with acrylics (will be thicker then what I had but all you have to add are the handle and paint it and it's finished)
6. The best is to look up the typical poses of a character such as Szayles typical sword drawing pose or his hand gestures. Look closely at the manga and anime and take notes on how he moves. if you have a sword finished look for some poses where it is seen (otherwise it would be useless anyway right?). If you want people to pay attention to a certain part of your outfit like the glasses make a pose pulling them in focus such as shoving them up your nose with one finger.
Hope I was somewhat helpful ^^