Subject: POSTERS

I'm thinking of printing posters from jpegs taken on 3.2 megapixel and 5 megapixel camera.Very clear photos, I have been told they would enlarge up to A1 size.
1.CAN YOU TELL ME IF THEY ARE GOOD QUALITY FOR A1 POSTERS IF YOU SEE THEM? (650megabites up to 850 mb).
2.How much do I have to pay to send from China to Australia?
3.Do I have to pay import/customs fee in Australia on top of postage? Do you know how much?
4.Can I use more than one image for poster? Example if I get 500 posters, is it all the same photo, or can I get 100 posters of 5 different images? (equalling 500 posters total).
5.If I write text on my poster,do you tell me if it won't fit in? As text Must be on my poster. (Inside the bleed if there is one).
6.Lastly, do posters arrive flat in box, or each rolled up in plastic or cardboard tube?

THANK YOU VERY MUCH, sorry so many questions.
Fran