On mixed marriages. For marriages between a Catholic and a non-Catholic, is it possible to have the marriage within the mass?

Yes, it is possible have the marriage rite within the Mass. The couple have to secure the permission of the Chancery Office and they have to comply with the necessary requirements for mixed marriages, i.e. Disparity of Cult Dispensation. A list of requirements and procedures to undertake should be readily available from the parishes, or you may contact the Chancery Office for more information.

Where do we post the banns - place of baptism where the baptized Catholic to be married is no longer a resident, or the place where the individuals to be married are residents for quite some time?

The banns are posted at the parish where the individuals are residents for many years after their 18th birhday