Job Interview help!

I have a job interview on Thursday and need advice. It's at a small town hospital (in the town I live) but even so I'd like to be prepared as possible.

I've had my LPN since June 2011 and my RN since September 2012. I've worked in long term care pretty much since I've had my LPN in June. I've interviewed at a smaller hospital than the one I'm interviewing at on Thursday (it was in a town 30 mins away) twice and didn't get called in for a second interview or anything. Just got the form letter in the mail. It's kind of disheartening because I really thought I did well. So I really, really want to do this interview right. I really want this job - it's 2 minutes from my house and it's not LTC which is pretty much what I'm asking for now. Here are my questions.

1. I was fired from my previous job - see my other posts. An accident occurred, the facility wanted me gone, so they wrote me up for everything they could find until they could fire me. I was told I was fired because I "falsified documentation" by writing the wrong date on a bandaid when I changed it. I don't want to lie to a potential employer but I also don't want to word it wrong or go into too much detail. The firing was last friday - not even a week ago - and I'm still emotional about it. Any tips?

2. How to dress? I have tattoos on my arms which can easily be covered with a long sleeve shirt. I also have a tattoo on the back of my neck and I have short hair which doesn't cover it. I was thinking a nice, dressy scarf to hide that. Long sleeve dressy top and nice slacks with some flats.

3. What were the hardest, most difficult questions they have ever asked you in an interview? What were the weirdest?

4. I've been told that I should try to be smiley and bubbly during an interview. What is your opinion on this?

Any other tips/advice would be helpful. I really need/want this job. I've applied for positions at this hospital before but they're notorious for hiring from within.

Thanks so much!!!:)