For the word length, it must be over 250 words but there is no upper limit. However, I usually recommend students to aim for between 260 to 280 words so that they have time to focus on quality rather than quantity. Writing a longer essay brings no benefits.
All the best
I have had many IELTS teachers asking such questions to me in the past. The latter approach you mentioned is less direct. While this is a good approach for many academic essays and may draw the attention of the reader, it is unnecessary for IELTS. An IELTS introduction should serve two purposes, as you said, to introduce the essay question and present your position. Anything more is unnecessary. This is a short academic essay with a strict time limit. The main bulk of the points awarded in IELTS writing task 2 come from the body paragraphs so extending the introduction further is a waste of time and words.
I practiced this essay and faced some conflicts. So I partially agree and wanted to present a balanced view, however in writing I had a lot of points, for both positives and negatives in mind and considering word limit, I was not able to elaborate properly.
* If your work exceeds the upper word limit by less than 10% the mark will be reduced by 10 percentage marks. Your mark cannot, however, be reduced below the minimum pass mark -- assuming that the work merited a pass.