I have 29" suitcase, would it be possible to carry on the bullet train? If not please advise.

Although they have a policy that the weight should be less than 20kg and size should be witin 130cm, they are not really strict with this policy. You can take the luggage with you directly. As long as the size is not extremely large, the luggage will not be measured at all. 29'' suitcase should not be a problem.

And yes! You can collect the ticket days in advance and this will save your trouble on the departure date.