Should candidates be informed of the type of interview they are invited to? (i.e. panel, one-on-one, etc.)

yes, the aim of the interview is to check employees KSAs (Knowledge, Skills & Attitude), so no problem to let the employee prepare and show how he can fit to the position.

Yes, in order to be ready and not be surprised candidate and thus may falter and dither

No.
I believe candidates should not be informed.
First, applicants have the tendency to impress and at times exceed what they are capable of just to get the job.
As an applicant, you are suggested to be true and bring your usual self during interview.
Second, informing applicants will not help in soliciting the truth about the applicant.
Let the credentials of the applicant speak for itself.
Finally, telling the applicants about the type of interview to be done will be detrimental to the interviewee.
It will cause distress to the applicant because they are already expecting something.
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It's better to specify the contact person that will make the interview to the candidate.
It gives more time to the candidate to can prepare himself.

The purpose of the SURPRISES is to understand the level of confidence the candidate has and his ability to how quickly he/she will adjust.
In my opinion there is nothing wrong in surprising the candidate with the panel of interviewers without telling him/her.
In one case I remember I was called for an interview in another city and the coordinator shared with me that I will meet Mr.
XXXX who is the Director HR.
I went there and met with the director HR but when the interview finished he asked me if i got some time I should meet the General Manager Operations.
So I met with that guy too and he further suggested me to meet the Managing Director of the Company.
To cut the story short I went for an interview to get a job so it doesn't matter if one person takes an interview or a group of people.
The objective is I should be ready to face anything coming on my way.

Absolutely, they should be.
That will help them prepare better for the interview and will also allow them to be more confident during the interview because of having prior knowledge about the type of interview.

In fairness to the interviewee, they should inform which kind of interview will it be.
Some interviewers want to surprise or caught people flat footed, I had an experience once and I felt cheated.
Though I pass the interview, I did not pursue the company.
I don't feel at ease and I had a notion that they cannot be trusted.

It is a professional way to inform the candidate about the details of the job interview as well as the result wether he or she passed or not.