Hi again @Kurra,
Thanks for sharing :),
Being prepared in advance is such a great strategy, both pre interview and at the interview, and demonstrates your professionalism and interest in the role. I agree, researching the company is an effective way to prepare for interview questions and also for you to assess if this is the sort of company you would be interested in working for.
Before calling, I think it works best to read the full job application and all materials so you have an understanding of the role, and this will no doubt come across when you are introducing yourself to the prospective employer/ contact officer, and you can tailor the information you share to the role.
So how many questions is too many questions? When speaking with a prospective employer, I think ringing up with 1 2 or 3 questions (at the most) is the way to go. You want to show your interest, and have questions ready, but you also want to respect the amount of time they have available. I personally like the idea introducing myself, expressing interest in the role (and perhaps company), and then asking two questions, being mindful of taking no more than 5 minutes of their time. And always thanking them for the time they have alocated, and letting them know you appreciate it.
And always build rapport with the person you are speaking with. Ie, asking them how they are, using their name in the conversation (but not too much) etc.
Look forward to hearing your thoughts and comments :).