First off - CA is Air China, a Star Alliance carrier. It would be much easier if people here used the carrier's name rather than their short code, particularly when they get the code wrong! You obviously mean CI, China Airlines.
To answer question number 1, if you are connecting on the same day, and with enough time to make the connection, then the check-in agent at Manchester should indeed be able to check your bags all the way through to BKK if you show them your onward ticket from Amsterdam. But allow enough time for your connection just in case this is not possible on the day.