Of course. You want to look your best and present yourself well wherever you go. Your dress sense in an interview should be smart and appropriate, but the main focus of the person that is interviewing you is your qualities and personality. They are professionals and understand what professionalism is. Judging by looks is not professional. But looks in terms of what you wear is important. 

---

They are very important, but shouldn't be.

---

I guess so!

---

It really depends, if your first impressions  are their looks that no it is not, but if you get to know them then yes it is.

---

Yes. A first impression is basically an overview of your personality in a nutshell.

---

depends on the person and situation.

---

Yes.
But it usually doesn't matter, they all grow to hate me.

---

to some people... 

---

They are very important (if you want people to like and think well of you) and hard to change. The human brain is hardwired to evaluate a person within the first 30 seconds of meeting them, and is involuntary. Everyone does it and you can't stop it. It was originally a survival instinct; you could never tell if someone approaching you was friend or foe and could mean the difference between life and death. Of course they aren't made in that sense nowadays, considering our circumstances have changed since those times. Now they're used to evaluate the information to make judgement calls.

---