有效期不够半年回国估计是可以的。
然后回去转长期签证。
或再来的时候重新申请旅游签证。
只是回答第三个问题
换了护照以后,把相关资料发给ICA,然后他们就会更新系统了。
这是ICA回复我的邮件:
Together with the applicants' new passport bio-data page, please also provide us with clear images of his/her Long-Term Visit Pass card (front) and local sponsor's NRIC so that we may verify and update our records. Please provide the images in jpeg or doc format. The updating is not available on the self-service web-portal.