Use I not we, the interviewer wants to know what you did. Agree have a list of questions it shows you are rely interested in the role, my go to q's are: What so you think will be my biggest challenge? Do you have an induction programme/will there be a handover? Is this a new role?/why is the current post holder leaving? Is there anything else you would like to know about that we haven't discussed?
Last question along the lines of it's been lovely to meet you, the role sounds really exciting/interesting, how many more stages are there to the interview process and who will you get back to me.
have a planned and rehearsed answer for the "tell me about you, why you want this post" question.
if you have to identify a negative, then be able to say.. I know i find ..... difficult/stress... but this is what I do .... when I come across this situation.
have some questions planned for the "have you any questions"... but something other than how much is the pay, when will I hear etc? One I liked was that the interviewee asked me what the favourite bit of my role was and what was the worst bit..