Interesting exercise.

5 MW would give you about 30-40 Petahash.  This assumes around 0.1 Joule/Gigahash, as for the Bitmain S9.

Capital cost would be about 5 to 10 million USD depending on building availability, miner hardware cost and what electrical infrastructure  (high voltage transformers etc) is needed.   See
https://bitcointalk.org/index.php?topic=1512967.0

If you don't have the capital to purchase your own miners the other approach to earning money is to just build and wire the building, and then host hardware.  But this is labor intensive and requires a support infrastructure.  To keep costs down you would need to limit mining users, say to just those who will pay for at least 50 Killowatts.