お誕生日
おめでとう
ございます
is good considering A4 poster.You can write her name both on the top of it and next line after ございます. It seems to me that the top is better.About question 2,it depends on how usually call her.If you call her Jyo sensei,it'd be OK.But if you call her Jyo san or Misao san,then I'd write simply write Jyo Misao san.