I just followed the instructions on the application. The way they bolded 'follow the directions' a few times made me think that most people don't. Answer the essay question, and try not to second guess what you think they want.
I will say Irish are not as self-promoting of a culture as American culture - it comes off as bragging/turns them off. It's more of a European vs. American difference in general. I wouldn't do the 'I'm so awesome so you should let me into your school.' I'd do more of the 'I learned a lot from x, y, z experience and become a better person for it and this is what I'd be able to contribute to the school.' I'm sure you'll get a wide range of answers from different people - after all most of us didn't see the others' essays. This is just my impression of the whole thing.
Stats wise - I feel once you have a certain gpa/mcat combo, then it doesn't matter as much - you've got your foot in the door so to speak. My rec letters were awesome, MCAT was decent, and gpa was probably the weak point. So basically I had strong areas to cover the weak ones.
Apply on time/early. I think getting it in by January is fine. I would do earlier if possible since I think they say their deadline is earlier (but quite a few people applied later than this). Rumor has it they start looking at all the apps in February/March and everything before that gets lumped together. After that it's rolling/you're at a disadvantage.
Interviews are for RCSI and Limerick iirc (RCSI for sure, Limerick can't remember) only. They seem to 1. want to make sure you can pay for it 2. want to make sure if you're offered a spot in Ireland you'll take it. Again, read over the feedback from other people in the other threads on this forum. I go to UCD, so I can't speak for the other schools as much.
Overall, I'd say don't stress too much. Just don't be a weirdo/douche, no using the personal essay for venting/revealing psychological problems, and try not to put people to sleep. Other than that you should have a decent essay. Assuming other areas are fine - then you've given it your best shot.
