A:Answer Having 2 drives will not complicate anything. You will need to reformat the partition currently holding Win7, and may need to reorganize any other partitions on the drive to make an install partition large enough to accommodate Win10.
If your storage drive is already formatted for Windows, there shouldn't be an issue. If you add a new drive in the future, see instructions below.
Once you have a fresh install, if your additional drive does not automatically show up after all drivers are installed, go to File Explorer, right click "This PC," and click "Manage" to access Disk Management. Check both to see if your second drive is listed, then format the drive and add desired partitions. This will allow Windows to see your drive.