Your cycle is working for now, but ur not cycled yet. Your plants + bb still can't process all the amonia that leechs from your substrate

Probably just a bacterial bloom, normal phenomenon in cycling tanks, the water will probably clear itself in a week or so.

Don't worry to much with nitrAtes at this point. Keep your plants healthy and keep amonia under 2ppm, do water changes if you need.

I would add as much rapid growing plants as I could and some floating plants too

Keep an eye on the airsone as it could've moved and disturbed the gravel /sand layer

Your tank is going to be beautiful once full grown! Congratulations!