Because, quite honestly, it's not all about you. I know that's kinda rude sounding - sorry! - but ... putting those tours together and Q&A sessions requires students to donate their time, and those are students who are trying to survive vet school. To do it all on Thursday (in-state), Friday AND Saturday just for applicant convenience is tough!
In regards to the "is it ok to not attend Q&A/tour" posts - sure. Nobody is judging your attendance at anything beyond the interview. That said, it is to your benefit to get as much information as possible.
In regards to the "what questions should we ask" post - anything of interest. Don't make up something to sound good - your interviewers genuinely aren't judging you based on your questions. It's just a chance for you to get more info if you want it! Really. Truly. Honestly. When you think about questions, if you are out of state (or not familiar with the area, anyway), consider questions about the area itself, not just the veterinary program.
I am not doing interviews this year because of scheduling, but I've done them the last few years, so I think my advice is likely reasonable.
The advice I've given in the past (this isn't giving away anything that is confidential) is this: Google "behavior-based job questions" (or something like that) and you can find plenty of lists of these types of questions. Spend some time with coffee or whatever in a peaceful place reflecting on your life - accomplishments, challenges, good relationships, bad relationships, meaningful events, jobs, volunteer activity. Just freshen it all up in your brain. Think about what challenges you faced, how you dealt with them, what the outcomes were, and what you learned from it. Then get a friend or relative or other trusted person and offer to buy them coffee and have them ask you behavior-based questions. Get your answers down to about 5 minutes or so. Remember that your answers should be drawn from real experiences/relationships, NOT a hypothetical. The single biggest mistake I see people making year after year is answering with a hypothetical. Questions typically start with "tell me about a time when .........." If your answer is "well, if I were in that situation, I'd do X" or whatever - you're probably on the wrong track. Remember that each question is designed to assess a personal characteristic, and that behavior-based questions are premised on the "past performance predicts future behavior" concept.
Best of luck to the candidates. Try to enjoy your visit. It is GENUINELY meant to be a positive visit and while everyone knows it is stressful for you, the staff and students really do want the best for you.