How to frame the art-work?
A3 and A2 sizes are standard sizes worldwide. Go to IKEA or Hema and you'll find a suitable frame for a very cheap price.
If you want to frame it very professionally and you have the budget, you can visit a professional frame maker. In Amsterdam I can recommend you Profilex; lovely people who understand the craft of frame making.
Another option is to glue it on Foamboard.
Foamboard is a super-light polyurethane foam sheet with two thin layers of aluminium and covered with paper. With a bit of glue and dubble sided tape, you'll have a perfect result.
Adhesive Foamboard can be called Centafix. Foamboard can be purchased at most regular painting supplies stores or online.
Wallpaper is made to be glued on the wall. Look at it as poster art for the interior. It is fast, cheap and simple. You only need some guts, an open mind and a bit of Wallpaper glue.