1. What "typical" contents does an admin dashboard contain?
2. Is there any design guideline available for creating an admin dashboard?
It really could be anything "transactional", not structural (in an ALM Deployed model). For instance, if this is in a data hub, it could be different validations of your data to ensure you are not missing and cost center/department/meta data that is currently defined within the transactional data or it could be different mappings that need to be defined, or Dynamic Cell Access. Essentially, items that can only be changed/updated by an admin and not an end user.
Hope this helps,
Something I had made for myself that can be very useful depending on your model: an archive module where I would copy the whole P&L (works with every final reporting module you have) and then check against the live calculation for any difference. I'd make a copy before starting some development this way I would know in a glance if a change I was doing had any impact at all on calculations.