1. Mine would be (per ad set/campaign)
- blended return/active ROAS at various points (3d, 7d, 14d, but various a lot depending on the title and UA strategy)
- Outbound CTR
- CPM
- CPI
- IR
- CPP
- # Unique payers
2. If running worldwide UA, often various country splits just muddle the picture.
3. For me that was tracking daily blended return for every single ad set (see below) -- it improved the agility of decision making.
4. Depending on the selection of metrics, I've seen people killing good campaigns and dragging the bad campaigns for longer. The most commonly overlooked metric is the number of unque payers, when one random whale "feeds" the losing campaign for weeks.
I've been using a very simple template to track daily ROAS by manual entry from the FB Ads Manager: https://docs.google.com/spreadsheets/d/1KbRzSemRn5ROYsl1jEfiodHmZI73IqF40woa2Es4tnI/edit#gid=1292744512
The template tracks blended return/active ROAS at various days which different depending on your title. I used it daily to assess the state of my campaigns and to make changes, which are also logged in this file, so you can see all the historical changes in there.
I know this might not be enough for everyone, but especially if your UA strategy is ROAS-centric and you know your KPIs, I found it really useful as a reporting and decision making tool. Ideally this one would be coupled with some of the more visual tools that ingest data directly from your accounts via API to give's you a bird's eye view on various metrics.