Hey, nice fish
I would suggest a bristlenose to keep control of that algae........ best algae eaters out there, and one would not bother your FM at all.
And by the way, the behaviour you spotted of the FM moving gravel....that is a normally a good indication they are getting ready to spawn.....especially if the gravel they are moving is near one of those flower pots.
One last thing...if it was my tank, I would swap the gravel for sand....then if anyone overfeeds whilst you are away it is much, much easier to vac the excess away.
Good luck with the fry when they arrive!
G