I have 2 in my 90g pH7.4 soft water tank.
These guys think that they are
so funny by freaking me out, lying on their backs to sleep
belly up.
They always do that at the front of the tank, right in plain sight. :roll:
I'm setting it up and want them to dig in the sand to avoid having poisonous air pockets.
There is gravel in my tank with the clowns and I can't say they "dig".
They will sort of snuffle some through the gravel. With sand it may be different, tho.
I just don't think they will "maintenance dig" like you envision they would. (your mileage may vary)
Mine will scanvenger for left over food, which includes any eggs laying around.
There is alot written about these guys, so research on Google is easy.
Everything I have read about them suggests getting more than 1, so I'm glad you are getting at least 2.
Please don't cycle your tank with these guys.

They are really nice fish and that'd be a shame.
If you are patient, you can train them to take food from your finger tips.
Mine swim throughout the water collum and are active through the day.
They can be shy. To take a break from everyone, mine like to wriggle in behind some slate that I have leaning against the back glass of the tank.
One other thing, be careful when handling them. For defence they have "razors" that can protrude from just below their eyes.
hth
Alicem