As long as you're comfortable with having to maintain the cross database queries there's nothing terrible about the idea.  And it definitely provides a nice way to isolate reporting development...

Well first, what happens when you try to run just the sqlcmd part of your batch file?

You'll need to format the string into something SQL Server can parse, https://docs.microsoft.com/en-us/sql/t-sql/functions/cast-and-convert-transact-sql it looks like you can use type 107 to convert into a date and do your...

Well storage is cheap and yes if you're trying to keep historical dimension data it's entirely expected you might end up with a much larger data warehouse than your sources....