hi, I'm new to this forum so I hope I can help.
I've been working with Excel for a very long time and I've some recommendations to think about your dashboard:
1) Which version(s) of Excel you'll be using?
2) Which database & system platform(s) you'll use?
3) Is there any help to get the data (data dictionary, knowledge base, db advice, etc)?
4) Do you've a final layout (I recommend at least an image)?
5) You'll need some data examples to validate your queries
6) Is it read-only (recommended)?
7) All data will be on the same database or you need to capture some values from another (unreachable) sources?
8) How much automatization (data update) will be involved in the process?
9) How fast the update must be? (could be seconds or minutes, depending on target user)
10) How much drill down you'll need
11) Verify needed credentials for all items (system, db, proxys, etc... also, only read-only users recommended)