Export userids and custom variables for specific page url

General questions
1

My client’s site has a user hirerachy - Technology center - Organization - user. Users access the site to analyze some forms and each form has a number. It is a HTML5 based application and so page visits are simulated.

In the visitor log screen, I could see the employee number (overwrite userid), the organization they belong to and the parent tech center (using custom variables). Form numbers are captured as part of the page url. So far everything is good.

The client wants a report - List of users accessing a particular form number with the hierarchy.
I setup a pageurl segment filtering a particular formnumber in the visitor log screen. It shows me all the visitors using that formnumber.
When I export it as a tcsv, it has a lot of lot of columns and the client is overwhelmed. I would like to provide just three columns - userid, tech center and organization in the exported tcsv report.

I have two questions and would really appreciate if someone could guide me here:

  1. From what I have read, the option is to develop a custom report. Before I venture into that, I just wanted to check if there is an alternative.
  2. If I also need a report UI, would Live API be the best option? I am expecting million page views every month, would this be still the best option? I will be turning on archiving and shutoff on-demand report generation altogether(using flag as given in the How-To section).
2

I wrote a custom report and used the Live API to get the list of userids using a particular page.
My concern is performance when it goes live with million page views per month.

I could preprocess them, but I don’t have any associated metrics to it. All I need is a flat list of user-ids and custom variables.
I will continue looking around to figure it out. Page URL is an example that creates a list of all unique page URLs. will just have to replace page URLs with user-id, cut out the other attributes and, replace them with custom variables values.