Hi. These are important questions for sure!
Yes, KCU's curriculum is rigorous, however, it prepares you really well for boards. The 2 pass curriculum allows you to go over every system twice before taking boards so you will have to study less because there aren't any concepts that you learned 2 years ago and never saw again like at other schools. I understand your concern bc I also struggle academically, I'm not going to lie, it's challenging but med school is hard everywhere you go, at least at KCU, I know the challenge is preparing me not just burning me out. There's also a ton of support and opportunities to overcome any difficulties you may have.
You absolutely can find that here. I'm a KC student and I have so much fun with my class, nobody has EVER been unfriendly to me. Every class culture is different and it does tend to change from year to year, what I will say is having 200 classmates gives you lots of opportunity to make friends. I'm sorry your interview day was negative, but I honestly never hear that from pre-meds and my interview day is what made me fall in love with KCU so maybe it was an off day.
Bottom line: you're going to find a handful of unhappy students at every school, but if I had to go back, I would choose KCU again for sure and that's part of the reason I am active in this forum. But honestly, if you felt like it was bad vibes and you're not a fit, then go with your gut. Feel free to DM me if you have anymore questions!