Keep in mind that the expense of recruiting, preparing, retraining of new staff is generally on the high side.
Regardless of how certified you think you are, using the phrase 'Yeah' as an alternative of 'Yes' can ruin your possibilities of getting employed.
It is not good sign if your phone rings in the middle of such a serious business interview and never ask permission to answer the call.
Answering "I don't know" to a difficult question asked makes you look rude, ignorant and lacking initiative.
Never tell the interviewer how much you hate your last job. Be civil, constructive, don't lie and be formal.